MIPS: asm: compiler: Add new macros to set ISA and arch asm annotations

There are certain places where the code uses .set mips32 or .set mips64
or .set arch=r4000. In preparation of MIPS R6 support, and in order to
use as less #ifdefs as possible, we define new macros to set similar
annotations for MIPS R6.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

arch/mips/include/asm/compiler.h

@@ -24,4 +24,17 @@
 #error "microMIPS compilation unsupported with GCC older than 4.9"
 #endif
 
+#ifdef CONFIG_CPU_MIPSR6
+#define MIPS_ISA_LEVEL "mips64r6"
+#define MIPS_ISA_ARCH_LEVEL MIPS_ISA_LEVEL
+#define MIPS_ISA_LEVEL_RAW mips64r6
+#define MIPS_ISA_ARCH_LEVEL_RAW MIPS_ISA_LEVEL_RAW
+#else
+/* MIPS64 is a superset of MIPS32 */
+#define MIPS_ISA_LEVEL "mips64r2"
+#define MIPS_ISA_ARCH_LEVEL "arch=r4000"
+#define MIPS_ISA_LEVEL_RAW mips64r2
+#define MIPS_ISA_ARCH_LEVEL_RAW MIPS_ISA_LEVEL_RAW
+#endif /* CONFIG_CPU_MIPSR6 */
+
 #endif /* _ASM_COMPILER_H */