MAINTAINERS: update Shawn's email address

My Freescale email address will be gone shortly.  Update my email to be
the Linaro one.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

MAINTAINERS

@@ -969,7 +969,7 @@ F:	arch/arm/include/asm/hardware/dec21285.h
 F:	arch/arm/mach-footbridge/
 
 ARM/FREESCALE IMX / MXC ARM ARCHITECTURE
-M:	Shawn Guo <shawn.guo@freescale.com>
+M:	Shawn Guo <shawn.guo@linaro.org>
 M:	Sascha Hauer <kernel@pengutronix.de>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained