[POWERPC] 32-bit early_init() should zero from __bss_start to __bss_stop only

Currently, early_init() in setup_32.c zeroes from '_bss_start' to '_end'.
It should only zero from '__bss_start' to '__bss_stop'.  This patch does that.
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/setup_32.c

@@ -92,7 +92,8 @@ unsigned long __init early_init(unsigned long dt_ptr)
 
 	/* First zero the BSS -- use memset_io, some platforms don't have
 	 * caches on yet */
-	memset_io((void __iomem *)PTRRELOC(&__bss_start), 0, _end - __bss_start);
+	memset_io((void __iomem *)PTRRELOC(&__bss_start), 0,
+			__bss_stop - __bss_start);
 
 	/*
 	 * Identify the CPU type and fix up code sections