microblaze: Invalidate dcache before enabling it

We found that on write-trough kernel is necessary to do that invalidation.
One WB is possible to use invalidation too.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

arch/microblaze/kernel/setup.c

@@ -54,6 +54,7 @@ void __init setup_arch(char **cmdline_p)
 
 	microblaze_cache_init();
 
+	invalidate_dcache();
 	enable_dcache();
 
 	invalidate_icache();