x86: use _ASM_EXTABLE macro in include/asm-x86/uaccess_64.h

Use the _ASM_EXTABLE macro from <asm/asm.h>, instead of open-coding
__ex_table entires in include/asm-x86/uaccess_64.h.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

include/asm-x86/uaccess_64.h

@@ -181,10 +181,7 @@ struct __large_struct { unsigned long buf[100]; };
 		"3:	mov %3,%0\n"				\
 		"	jmp 2b\n"				\
 		".previous\n"					\
-		".section __ex_table,\"a\"\n"			\
-		"	.align 8\n"				\
-		"	.quad 1b,3b\n"				\
-		".previous"					\
+		_ASM_EXTABLE(1b,3b)				\
 		: "=r"(err)					\
 		: ltype (x), "m"(__m(addr)), "i"(errno), "0"(err))
 
@@ -226,10 +223,7 @@ do {									\
 		"	xor"itype" %"rtype"1,%"rtype"1\n"	\
 		"	jmp 2b\n"				\
 		".previous\n"					\
-		".section __ex_table,\"a\"\n"			\
-		"	.align 8\n"				\
-		"	.quad 1b,3b\n"				\
-		".previous"					\
+		_ASM_EXTABLE(1b,3b)				\
 		: "=r"(err), ltype (x)				\
 		: "m"(__m(addr)), "i"(errno), "0"(err))