MIPS: fix mips_cache fallback without __builtin_mips_cache

The "R" constraint supplies the address of an variable in a register. Use
"r" instead and adjust asm to supply the content of addr in a register
instead.

Fixes: 2b8bcc5a ("MIPS: avoid .set ISA for cache operations")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

arch/mips/include/asm/cacheops.h

@@ -16,7 +16,7 @@ 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));
+	__asm__ __volatile__("cache %0, 0(%1)" : : "i"(op), "r"(addr));
 #endif
 }