ath5k: remove conf->beacon_int usage

ath5k: remove conf->beacon_int usage

ieee80211_conf->beacon_int was deprecated and removed in a cleanup
patch, however it was accidentally added back to ath5k in the change
"ath5k: Allow user/driver to set txpower."  Remove it once more,
fixing the following warning:

[13091.968902] WARNING: at drivers/net/wireless/ath/ath5k/base.c:2167 warn_slowpath_null+0x15/0x1a()
[13091.968906] Hardware name: MacBook1,1
[13091.968909] Modules linked in: usb_storage fuse i915 drm af_packet acpi_cpufreq binfmt_misc dm_mirror dm_region_hash dm_log dm_multipath dm_mod snd_hda_codec_idt snd_hda_intel snd_hda_codec snd_seq_dummy hid_apple arc4 ecb snd_seq_oss snd_seq_midi_event usbhid snd_seq ath5k mac80211 appletouch snd_seq_device snd_pcm_oss snd_mixer_oss sky2 snd_pcm ath processor cfg80211 snd_timer sg ohci1394 snd uhci_hcd bitrev ieee1394 joydev ehci_hcd crc32 snd_page_alloc button ac thermal battery sr_mod applesmc cdrom evdev input_polldev unix [last unloaded: microcode]
[13091.968985] Pid: 2132, comm: phy0 Tainted: G        W  2.6.30-rc5-wl #118
[13091.968988] Call Trace:
[13091.968994]  [<c0125884>] warn_slowpath_fmt+0x77/0xa6
[13091.969003]  [<c03557d8>] ? _spin_unlock+0x2c/0x41
[13091.969008]  [<c0355a56>] ? _spin_lock_irqsave+0x15/0x69
[13091.969012]  [<c0355783>] ? _spin_unlock_irqrestore+0x34/0x5d
[13091.969019]  [<c01445bb>] ? trace_hardirqs_off+0xb/0xd
[13091.969024]  [<c0355783>] ? _spin_unlock_irqrestore+0x34/0x5d
[13091.969029]  [<c01445bb>] ? trace_hardirqs_off+0xb/0xd
[13091.969034]  [<c0355783>] ? _spin_unlock_irqrestore+0x34/0x5d
[13091.969039]  [<c01258c8>] warn_slowpath_null+0x15/0x1a
[13091.969054]  [<f965846d>] ath5k_beacon_update_timers+0x44/0x27f [ath5k]
[13091.969059]  [<c0126370>] ? vprintk+0x2dd/0x312
[13091.969063]  [<c0125e50>] ? release_console_sem+0x1a6/0x1d3
[13091.969076]  [<f96586c5>] ath5k_reset_tsf+0x1d/0x2c [ath5k]
[13091.969095]  [<f93f4426>] __ieee80211_sta_join_ibss+0x35/0x3aa [mac80211]
[13091.969102]  [<c0252793>] ? extract_entropy+0x47/0x8a
[13091.969121]  [<f93f4b21>] ieee80211_sta_find_ibss+0x2de/0x32f [mac80211]
[13091.969126]  [<c035422c>] ? mutex_lock_nested+0x28b/0x2a5
[13091.969145]  [<f93f4b8e>] ? ieee80211_ibss_notify_scan_completed+0x1c/0x6f [mac80211]
[13091.969164]  [<f93f4bc9>] ieee80211_ibss_notify_scan_completed+0x57/0x6f [mac80211]
[13091.969182]  [<f93f26da>] ieee80211_scan_completed+0x31a/0x33f [mac80211]
[13091.969201]  [<f93f27ca>] ieee80211_scan_work+0xcb/0x18b [mac80211]
[13091.969207]  [<c0133a6a>] worker_thread+0x1b1/0x28e
[13091.969212]  [<c0133a25>] ? worker_thread+0x16c/0x28e
[13091.969230]  [<f93f26ff>] ? ieee80211_scan_work+0x0/0x18b [mac80211]
[13091.969237]  [<c013736e>] ? autoremove_wake_function+0x0/0x38
[13091.969242]  [<c01338b9>] ? worker_thread+0x0/0x28e
[13091.969246]  [<c0137031>] kthread+0x4a/0x70
[13091.971460]  [<c0136fe7>] ? kthread+0x0/0x70
[13091.971467]  [<c0103527>] kernel_thread_helper+0x7/0x10
[13091.971470] ---[ end trace 8defaa5d15c50cef ]---

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>