[PPC] 8xx: Fix r3 trashing due to 8MB TLB page instantiation

Instantiation of 8MB pages on the TLB cache for the kernel static
mapping trashes r3 register on !CONFIG_8xx_CPU6 configurations.
This ensures r3 gets saved and restored.

This has been posted to linuxppc-embedded by Marcelo Tosatti
<marcelo@kvack.org>, but only an incomplete version of the patch
has been applied in c51e078f82096a7d35ac8ec2416272e843a0e1c4.
This patch adds the rest of the fix.

Signed-off-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/ppc/kernel/head_8xx.S

@@ -495,9 +495,7 @@ LoadLargeDTLB:
 	lwz	r11, 4(r0)
 
 	lwz	r12, 16(r0)
-#ifdef CONFIG_8xx_CPU6
 	lwz	r3, 8(r0)
-#endif
 	rfi
 
 /* This is the data TLB error on the MPC8xx.  This could be due to