MIPS: fix inconsistency in config option for cache operation mode

Commit ab2a98b11716364bc5a8c43cdfa7fee176cda1d8 missed to
use the new config option in dcache_enable().

Fix this to avoid inconsistencies if someone wants to disable
and enable D-caches.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>

arch/mips/cpu/mips32/cache.S

@@ -30,6 +30,10 @@
 #include <asm/addrspace.h>
 #include <asm/cacheops.h>
 
+#ifndef CONFIG_SYS_MIPS_CACHE_MODE
+#define CONFIG_SYS_MIPS_CACHE_MODE CONF_CM_CACHABLE_NONCOHERENT
+#endif
+
 #define RA		t8
 
 /*
@@ -224,7 +228,7 @@ LEAF(dcache_enable)
 	mfc0	t0, CP0_CONFIG
 	ori	t0, CONF_CM_CMASK
 	xori	t0, CONF_CM_CMASK
-	ori	t0, CONF_CM_CACHABLE_NONCOHERENT
+	ori	t0, CONFIG_SYS_MIPS_CACHE_MODE
 	mtc0	t0, CP0_CONFIG
 	jr	ra
 	END(dcache_enable)