ARM: imx: Update MAINTAINERS file globs for i.MX8MP DHSOM

Update the MAINTAINERS file glob to cover all of i.MX8MP DHSOM related files.

Signed-off-by: Marek Vasut <marex@denx.de>

board/dhelectronics/dh_imx8mp/MAINTAINERS

@@ -2,7 +2,5 @@ DH electronics DHCOM i.MX8M Plus and matching carrier boards
 M:	Marek Vasut <marex@denx.de>
 L:	u-boot@dh-electronics.com
 S:	Maintained
-F:	arch/arm/dts/imx8mp-dhcom*
-F:	board/dhelectronics/dh_imx8mp/
-F:	configs/imx8mp_dhcom*defconfig
-F:	include/configs/imx8mp_dhcom*
+N:	imx8mp.*dh[cs]o
+N:	dh_imx8mp