microblaze: UMS is used only for MMU kernel

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 4201c74..c592d47 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -235,7 +235,9 @@
 	regs->pc = pc;
 	regs->r1 = usp;
 	regs->pt_mode = 0;
+#ifdef CONFIG_MMU
 	regs->msr |= MSR_UMS;
+#endif
 }
 
 #ifdef CONFIG_MMU