x86/apb/timer: Remove unnecessary "if"

adev has no chance to be NULL, so we don't need to check it. It
is also dereferenced just before the check .

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/r/1358199561-15518-1-git-send-email-dinggnu@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>