powerpc/47x: Base ppc476 support

This patch adds the base support for the 476 processor.  The code was
primarily written by Ben Herrenschmidt and Torez Smith, but I've been
maintaining it for a while.

The goal is to have a single binary that will run on 44x and 47x, but
we still have some details to work out.  The biggest is that the L1 cache
line size differs on the two platforms, but it's currently a compile-time
option.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 7ffbb65..7ebf42e 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -18,6 +18,7 @@
 #define MMU_FTR_TYPE_44x		ASM_CONST(0x00000008)
 #define MMU_FTR_TYPE_FSL_E		ASM_CONST(0x00000010)
 #define MMU_FTR_TYPE_3E			ASM_CONST(0x00000020)
+#define MMU_FTR_TYPE_47x		ASM_CONST(0x00000040)
 
 /*
  * This is individual features