x86: Fix a bogus unwind annotation in lib/semaphore_32.S

'simple' would have required specifying current frame address
and return address location manually, but that's obviously not
the case (and not necessary) here.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4D6D1082020000780003454C@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>