microblaze: Clear all MSR flags on the first kernel instruction

The main reason is bug because of dynamic TLB allocation.
U-BOOT didn't disable dcache and then writing to physical address
from ASM wan't visible for reading through MMU.
Disabling caches and clearing all flags from previous code
is good to do so.

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/head.S

@@ -63,16 +63,15 @@ ENTRY(_start)
 real_start:
 #endif
 
-	mfs	r1, rmsr
-	andi	r1, r1, ~2
-	mts	rmsr, r1
+	mts	rmsr, r0
 /*
  * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc'
  * if the msrclr instruction is not enabled. We use this to detect
  * if the opcode is available, by issuing msrclr and then testing the result.
  * r8 == 0 - msr instructions are implemented
  * r8 != 0 - msr instructions are not implemented
  */
+	mfs	r1, rmsr
 	msrclr	r8, 0 /* clear nothing - just read msr for test */
 	cmpu	r8, r8, r1 /* r1 must contain msr reg content */