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: Adam Ford <aford173@gmail.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng 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*/