MIPS: KVM: Fix pre-r6 ll/sc instructions on r6

The atomic KVM register access macros in kvm_host.h (for the guest Cause
register with KVM in trap & emulate mode) use ll/sc instructions,
however they still .set mips3, which causes pre-MIPSr6 instruction
encodings to be emitted, even for a MIPSr6 build.

Fix it to use MIPS_ISA_ARCH_LEVEL as other parts of arch/mips already
do.

Signed-off-by: James Hogan <[e-mail]>
Cc: Paolo Bonzini <[e-mail]>
Cc: Radim KrÄmář <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Paolo Bonzini <[e-mail]>

arch/mips/include/asm/kvm_host.h

···
 	unsigned long temp;
 	do {
 		__asm__ __volatile__(
-		"	.set	mips3				\n"
+		"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 		"	" __LL "%0, %1				\n"
 		"	or	%0, %2				\n"
 		"	" __SC	"%0, %1				\n"
···
 	unsigned long temp;
 	do {
 		__asm__ __volatile__(
-		"	.set	mips3				\n"
+		"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 		"	" __LL "%0, %1				\n"
 		"	and	%0, %2				\n"
 		"	" __SC	"%0, %1				\n"
···
 	unsigned long temp;
 	do {
 		__asm__ __volatile__(
-		"	.set	mips3				\n"
+		"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 		"	" __LL "%0, %1				\n"
 		"	and	%0, %2				\n"
 		"	or	%0, %3				\n"