MAINTAINERS: Update mx6 PCI driver maintainer's email

Use Shawn's email address from Freescale.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Shawn Guo <shawn.guo@freescale.com>

MAINTAINERS

@@ -6774,7 +6774,7 @@ F:	arch/x86/kernel/quirks.c
 
 PCI DRIVER FOR IMX6
 M:	Richard Zhu <r65037@freescale.com>
-M:	Shawn Guo <shawn.guo@linaro.org>
+M:	Shawn Guo <shawn.guo@freescale.com>
 L:	linux-pci@vger.kernel.org
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained