microblaze: Extend cpuinfo for support write-back caches

There is missing checking agains PVR but this is not important
for now. There are some missing checking too.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/kernel/cpu/mb.c b/arch/microblaze/kernel/cpu/mb.c
index 4dcfccd..0c912b2 100644
--- a/arch/microblaze/kernel/cpu/mb.c
+++ b/arch/microblaze/kernel/cpu/mb.c
@@ -103,11 +103,15 @@
 	else
 		count += seq_printf(m, "Icache:\t\tno\n");
 
-	if (cpuinfo.use_dcache)
+	if (cpuinfo.use_dcache) {
 		count += seq_printf(m,
 				"Dcache:\t\t%ukB\n",
 				cpuinfo.dcache_size >> 10);
-	else
+		if (cpuinfo.dcache_wb)
+			count += seq_printf(m, "\t\twrite-back\n");
+		else
+			count += seq_printf(m, "\t\twrite-through\n");
+	} else
 		count += seq_printf(m, "Dcache:\t\tno\n");
 
 	count += seq_printf(m,