kvm: qemu: kill some redundant declarations

kvm: qemu: kill some redundant declarations

Fixes:

  qemu/vl.c:5295: warning: redundant redeclaration of ‘kvm_pit’
  qemu/vl.c:5289: warning: previous declaration of ‘kvm_pit’ was here
  qemu/vl.c:5541: warning: redundant redeclaration of ‘kvm_allowed’
  qemu/qemu-kvm.h:144: warning: previous declaration of ‘kvm_allowed’ was here
  qemu/qemu-kvm.h:144: warning: redundant redeclaration of ‘kvm_allowed’
  qemu/qemu-kvm.c:11: warning: previous definition of ‘kvm_allowed’ was here
  qemu/qemu-kvm.h:145: warning: redundant redeclaration of ‘kvm_nested’
  qemu/qemu-kvm.c:15: warning: previous definition of ‘kvm_nested’ was here
  qemu/kvm-tpr-opt.c:22: warning: redundant redeclaration of ‘kvm_context’
  qemu/qemu-kvm.h:146: warning: previous declaration of ‘kvm_context’ was here
  qemu/qemu-kvm-x86.c:27: warning: redundant redeclaration of ‘kvm_context’

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>