MIPS: mipsregs: Set proper ISA level for virt extensions

c994a3ec7ecc ("MIPS: set mips32r5 for virt extensions") setted
some instructions in virt extensions to ISA level mips32r5.

However TLB related vz instructions was leftover, also this
shouldn't be done to a R5 or R6 kernel buid.

Reorg macros to set ISA level as needed when _ASM_SET_VIRT
is called.

Signed-off-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/include/asm/mipsregs.h

···
 		_ASM_INSN_IF_MIPS(0x4200000c)				\
 		_ASM_INSN32_IF_MM(0x0000517c)
 #else	/* !TOOLCHAIN_SUPPORTS_VIRT */
-#define _ASM_SET_VIRT ".set\tvirt\n\t"
+#if MIPS_ISA_REV >= 5
+#define _ASM_SET_VIRT_ISA
+#elif defined(CONFIG_64BIT)
+#define _ASM_SET_VIRT_ISA ".set\tmips64r5\n\t"
+#else
+#define _ASM_SET_VIRT_ISA ".set\tmips32r5\n\t"
+#endif
+#define _ASM_SET_VIRT _ASM_SET_VIRT_ISA ".set\tvirt\n\t"
 #define _ASM_SET_MFGC0	_ASM_SET_VIRT
 #define _ASM_SET_DMFGC0	_ASM_SET_VIRT
 #define _ASM_SET_MTGC0	_ASM_SET_VIRT
···
 ({ int __res;								\
 	__asm__ __volatile__(						\
 		".set\tpush\n\t"					\
-		".set\tmips32r5\n\t"					\
 		_ASM_SET_MFGC0						\
 		"mfgc0\t%0, " #source ", %1\n\t"			\
 		_ASM_UNSET_MFGC0					\
···
 ({ unsigned long long __res;						\
 	__asm__ __volatile__(						\
 		".set\tpush\n\t"					\
-		".set\tmips64r5\n\t"					\
 		_ASM_SET_DMFGC0						\
 		"dmfgc0\t%0, " #source ", %1\n\t"			\
 		_ASM_UNSET_DMFGC0					\
···
 do {									\
 	__asm__ __volatile__(						\
 		".set\tpush\n\t"					\
-		".set\tmips32r5\n\t"					\
 		_ASM_SET_MTGC0						\
 		"mtgc0\t%z0, " #register ", %1\n\t"			\
 		_ASM_UNSET_MTGC0					\
···
 do {									\
 	__asm__ __volatile__(						\
 		".set\tpush\n\t"					\
-		".set\tmips64r5\n\t"					\
 		_ASM_SET_DMTGC0						\
 		"dmtgc0\t%z0, " #register ", %1\n\t"			\
 		_ASM_UNSET_DMTGC0					\