powerpc: Don't set HAVE_EFFICIENT_UNALIGNED_ACCESS on little endian builds

POWER7 takes alignment exceptions on some unaligned addresses, so
disable HAVE_EFFICIENT_UNALIGNED_ACCESS. This fixes an early boot
issue in the printk code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/Kconfig

@@ -97,7 +97,7 @@ config PPC
 	select VIRT_TO_BUS if !PPC64
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
-	select HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_LITTLE_ENDIAN
 	select HAVE_KPROBES
 	select HAVE_ARCH_KGDB
 	select HAVE_KRETPROBES