[ARM] Switch CPU to BE mode before uncompressing when running BE

This is needed for certain systems (IXP2000,IXP1200) where the bootloader 
switches back to LE before jumping into the kernel or when we are trying
to boot a BE kernel from an LE bootloader.
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>

arch/arm/boot/compressed/Makefile

@@ -51,6 +51,10 @@ ifeq ($(CONFIG_DEBUG_ICEDCC),y)
 OBJS            += ice-dcc.o
 endif
 
+ifeq ($(CONFIG_CPU_BIG_ENDIAN),y)
+OBJS		+= big-endian.o
+endif
+
 #
 # We now have a PIC decompressor implementation.  Decompressors running
 # from RAM should not define ZTEXTADDR.  Decompressors running directly

arch/arm/boot/compressed/big-endian.S

+/*
+ *  linux/arch/arm/boot/compressed/big-endian.S
+ *
+ *  Switch CPU into big endian mode.
+ *  Author: Nicolas Pitre
+ */
+
+	.section ".start", #alloc, #execinstr
+
+	mrc	p15, 0, r0, c1, c0, 0	@ read control reg
+	orr	r0, r0, #(1 << 7)	@ enable big endian mode
+	mcr	p15, 0, r0, c1, c0, 0	@ write control reg
+