arm64: dts: imx8mm-evk-dpdk: dts for fec-uio driver

commit ea16443973a53b3d833da29a5f23a4c9aaa799c7 from
https://github.com/nxp-imx/linux-imx.git



Adding workaround: deleting property 'reset-assert-us' from DTS file
'imx8mm-evk-dpdk.dts'as these features are yet not supported in
fec-uio driver. Later we will revert the patch when feature is
supported.

Signed-off-by: Apeksha Gupta <apeksha.gupta@nxp.com>
DPDK-3875
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>