x86: Fix compile error with CONFIG_AS_CFI=n

AS      arch/x86/lib/csum-copy_64.o
arch/x86/lib/csum-copy_64.S: Assembler messages:
arch/x86/lib/csum-copy_64.S:48: Error: Macro `ignore' was already defined
make[1]: *** [arch/x86/lib/csum-copy_64.o] Error 1
make: *** [arch/x86/lib] Error 2

It appears that csum-copy_64.S and dwarf2.h both define an ignore macro. 
I would expect one of them can be renamed quite easily, unless they 
are references elsewhere. 

Caused-by-commit: 392a0fc96b
    x86: merge dwarf2 headers

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/dwarf2.h

@@ -38,23 +38,23 @@
 
 /* Due to the structure of pre-exisiting code, don't use assembler line
    comment character # to ignore the arguments. Instead, use a dummy macro. */
-.macro ignore a=0, b=0, c=0, d=0
+.macro cfi_ignore a=0, b=0, c=0, d=0
 .endm
 
-#define CFI_STARTPROC	ignore
-#define CFI_ENDPROC	ignore
-#define CFI_DEF_CFA	ignore
-#define CFI_DEF_CFA_REGISTER	ignore
-#define CFI_DEF_CFA_OFFSET	ignore
-#define CFI_ADJUST_CFA_OFFSET	ignore
-#define CFI_OFFSET	ignore
-#define CFI_REL_OFFSET	ignore
-#define CFI_REGISTER	ignore
-#define CFI_RESTORE	ignore
-#define CFI_REMEMBER_STATE ignore
-#define CFI_RESTORE_STATE ignore
-#define CFI_UNDEFINED ignore
-#define CFI_SIGNAL_FRAME ignore
+#define CFI_STARTPROC	cfi_ignore
+#define CFI_ENDPROC	cfi_ignore
+#define CFI_DEF_CFA	cfi_ignore
+#define CFI_DEF_CFA_REGISTER	cfi_ignore
+#define CFI_DEF_CFA_OFFSET	cfi_ignore
+#define CFI_ADJUST_CFA_OFFSET	cfi_ignore
+#define CFI_OFFSET	cfi_ignore
+#define CFI_REL_OFFSET	cfi_ignore
+#define CFI_REGISTER	cfi_ignore
+#define CFI_RESTORE	cfi_ignore
+#define CFI_REMEMBER_STATE cfi_ignore
+#define CFI_RESTORE_STATE cfi_ignore
+#define CFI_UNDEFINED cfi_ignore
+#define CFI_SIGNAL_FRAME cfi_ignore
 
 #endif