microblaze: Move CONFIG_LMB from board file to config.h

It is common for the whole architecture that's why move it there.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/microblaze/include/asm/config.h b/arch/microblaze/include/asm/config.h
index 45966ee..d522669 100644
--- a/arch/microblaze/include/asm/config.h
+++ b/arch/microblaze/include/asm/config.h
@@ -6,6 +6,8 @@
 #ifndef _ASM_CONFIG_H_
 #define _ASM_CONFIG_H_
 
+#define CONFIG_LMB
+
 #ifndef CONFIG_SPL_BUILD
 #define CONFIG_NEEDS_MANUAL_RELOC
 #endif