microblaze: Enable DTC compilation

For simpleImage format we need to compile DTC. There is still possibility
to compile only Linux kernel without DTB compiled-in.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 165cf06..fd53e50 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -79,6 +79,9 @@
 config NO_DMA
 	def_bool y
 
+config DTC
+	def_bool y
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"