[MIPS] TX49XX has prefetch.
    
The TX49XX has the prefetch instruction.  It supports only Pref_Load
(hint 0).  Actually changes in this patch except for Kconfig are not
have any effects, I added these changes to prevent misuse of unsupported
hints.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 9572ed44..32b7f6a 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -786,6 +786,7 @@
 		c->dcache.waybit = 0;
 
 		c->options |= MIPS_CPU_CACHE_CDEX_P;
+		c->options |= MIPS_CPU_PREFETCH;
 		break;
 
 	case CPU_R4000PC: