MAINTAINERS: Add imx dts files to i.MX maintainers list

Add imx dts files to the MAINTAINERS file list, so that i.MX
devicetree related patches can be properly sent to the i.MX folks.
Reported-by: NAdam Ford <aford173@gmail.com>
Signed-off-by: NFabio Estevam <festevam@gmail.com>
Reviewed-by: NPeng Fan <peng.fan@nxp.com>

MAINTAINERS

@@ -157,6 +157,7 @@ T:	git git://git.denx.de/u-boot-imx.git
 F:	arch/arm/cpu/arm1136/mx*/
 F:	arch/arm/cpu/arm926ejs/mx*/
 F:	arch/arm/cpu/armv7/vf610/
+F:	arch/arm/dts/*imx*
 F:	arch/arm/mach-imx/
 F:	arch/arm/include/asm/arch-imx/
 F:	arch/arm/include/asm/arch-mx*/