drivers/dma/iop-adma: Use dma_alloc_writecombine() kernel-style

drivers/dma/iop-adma: Use dma_alloc_writecombine() kernel-style

dma_alloc_writecombine()'s call and return value check is
tangled in all in one call. Untangle both calls according to
kernel coding style.

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: benh@kernel.crashing.org
Cc: bhelgaas@google.com
Cc: daniel.vetter@ffwll.ch
Cc: dmaengine@vger.kernel.org
Cc: konrad.wilk@oracle.com
Cc: luto@amacapital.net
Cc: mst@redhat.com
Cc: tomi.valkeinen@ti.com
Cc: toshi.kani@hp.com
Cc: xen-devel@lists.xensource.com
Link: http://lkml.kernel.org/r/1440443613-13696-10-git-send-email-mcgrof@do-not-panic.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>