MIPS: mipsmtregs: Fix target register for MFTC0

Target register of mftc0 should be __res instead of $1, this is
a leftover from old .insn code.

Fixes: dd6d29a6 ("MIPS: Implement microMIPS MT ASE helpers")
Cc: stable@vger.kernel.org
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/include/asm/mipsmtregs.h

@@ -322,7 +322,7 @@ static inline void ehb(void)
 	"	.set	push				\n"	\
 	"	.set	"MIPS_ISA_LEVEL"		\n"	\
 	_ASM_SET_MFTC0							\
-	"	mftc0	$1, " #rt ", " #sel "		\n"	\
+	"	mftc0	%0, " #rt ", " #sel "		\n"	\
 	_ASM_UNSET_MFTC0						\
 	"	.set	pop				\n"	\
 	: "=r" (__res));						\