MIPS: avoid .set ISA for cache operations

As a step towards unifying the cache maintenance code for mips32 &
mips64 CPUs, stop using ".set <ISA>" directives in the more developed
mips32 version of the code. Instead, when present make use of the GCC
builtin for emitting a cache instruction. When not present, simply don't
bother with the .set directives since U-boot always builds with
-march=mips32 or higher anyway.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

arch/mips/include/asm/cacheops.h

@@ -11,6 +11,19 @@
 #ifndef	__ASM_CACHEOPS_H
 #define	__ASM_CACHEOPS_H
 
+#ifndef __ASSEMBLY__
+
+static inline void mips_cache(int op, const volatile void *addr)
+{
+#ifdef __GCC_HAVE_BUILTIN_MIPS_CACHE
+	__builtin_mips_cache(op, addr);
+#else
+	__asm__ __volatile__("cache %0, %1" : : "i"(op), "R"(addr))
+#endif
+}
+
+#endif /* !__ASSEMBLY__ */
+
 /*
  * Cache Operations available on all MIPS processors with R4000-style caches
  */