x86, msr: Fix msr-reg.S compilation with gas 2.16.1, on 32-bit too

The macro was defined in the 32-bit path as well - breaking the
build on 32-bit platforms:

  arch/x86/lib/msr-reg.S: Assembler messages:
  arch/x86/lib/msr-reg.S:53: Error: Bad macro parameter list
  arch/x86/lib/msr-reg.S:100: Error: invalid character '_' in mnemonic
  arch/x86/lib/msr-reg.S:101: Error: invalid character '_' in mnemonic

Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <tip-f6909f394c2d4a0a71320797df72d54c49c5927e@git.kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/lib/msr-reg.S

@@ -50,7 +50,7 @@ ENDPROC(native_\op\()_safe_regs)
 
 #else /* X86_32 */
 
-.macro op_safe_regs op:req
+.macro op_safe_regs op
 ENTRY(native_\op\()_safe_regs)
 	CFI_STARTPROC
 	pushl_cfi %ebx