microblaze: mm: Use ZONE_DMA instead of ZONE_NORMAL

We should use ZONE_DMA because all address space is dma-able.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index c8d6efb..8e9da3d 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -27,6 +27,9 @@
 config RWSEM_GENERIC_SPINLOCK
 	def_bool y
 
+config ZONE_DMA
+	def_bool y
+
 config RWSEM_XCHGADD_ALGORITHM
 	bool