powerpc/cpm: Clear muram before it is in use.

We need to ensure that MURAM is in a known and cleared out state before
using it as the bootloader could have utilized it from its own purposes
and left it in an unknown state.

If we don't clear it out we've seen issues with UCC ethernet:
* Multi ethernet interfaces can't work simultanously.
* Multi up/down Ethernet interfaces will halt these ports.
* UCC1 RGMII can't work when kernel boots from some hosts.
Signed-off-by: NKai.Jiang <Kai.Jiang@freescale.com>
Signed-off-by: NHongjun Chen <Hong-jun.Chen@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

arch/powerpc/sysdev/cpm_common.c

@@ -3,7 +3,7 @@
  *
  * Author: Scott Wood <scottwood@freescale.com>
  *
- * Copyright 2007 Freescale Semiconductor, Inc.
+ * Copyright 2007-2008,2010 Freescale Semiconductor, Inc.
  *
  * Some parts derived from commproc.c/cpm2_common.c, which is:
  * Copyright (c) 1997 Dan error_act (dmalek@jlc.net)
@@ -146,6 +146,7 @@ unsigned long cpm_muram_alloc(unsigned long size, unsigned long align)
 	spin_lock_irqsave(&cpm_muram_lock, flags);
 	cpm_muram_info.alignment = align;
 	start = rh_alloc(&cpm_muram_info, size, "commproc");
+	memset(cpm_muram_addr(start), 0, size);
 	spin_unlock_irqrestore(&cpm_muram_lock, flags);
 
 	return start;