MIPS: ftrace: Fix a microMIPS build problem

commit aedd153f upstream.

Code before the .fixup section needs to have the .insn directive.
This has no side effects on MIPS32/64 but it affects the way microMIPS
loads the address for the return label.

Fixes the following build problem:
mips-linux-gnu-ld: arch/mips/built-in.o: .fixup+0x4a0: Unsupported jump between
ISA modes; consider recompiling with interlinking enabled.
mips-linux-gnu-ld: final link failed: Bad value
Makefile:819: recipe for target 'vmlinux' failed

The fix is similar to 1658f914 ("MIPS: microMIPS:
Disable LL/SC and fix linker bug.")
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8117/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/mips/include/asm/ftrace.h

@@ -24,7 +24,7 @@ do {							\
 	asm volatile (					\
 		"1: " load " %[" STR(dst) "], 0(%[" STR(src) "])\n"\
 		"   li %[" STR(error) "], 0\n"		\
-		"2:\n"					\
+		"2: .insn\n"				\
 							\
 		".section .fixup, \"ax\"\n"		\
 		"3: li %[" STR(error) "], 1\n"		\
@@ -46,7 +46,7 @@ do {						\
 	asm volatile (				\
 		"1: " store " %[" STR(src) "], 0(%[" STR(dst) "])\n"\
 		"   li %[" STR(error) "], 0\n"	\
-		"2:\n"				\
+		"2: .insn\n"			\
 						\
 		".section .fixup, \"ax\"\n"	\
 		"3: li %[" STR(error) "], 1\n"	\