imx: support i.MX8QM DMSSE20 a1 board

Add i.MX8QM DMSSE20 a1 board support

U-Boot 2023.04-00030-g7be2f547b2 (Apr 21 2023 - 11:11:43 +0200)

Model: Advantech iMX8QM DMSSE20
Board: DMS-SE20A1 8GB
Build: SCFW 549b1e18, SECO-FW c9de51c0, ATF 5782363
Boot: USB
DRAM: 8 GiB
Core: 100 devices, 19 uclasses, devicetree: separate
MMC: FSL_SDHC: 0, FSL_SDHC: 1, FSL_SDHC: 2
Loading Environment from MMC... OK
In: serial@5a060000
Out: serial@5a060000
Err: serial@5a060000
Net: eth0: ethernet@5b040000
Warning: ethernet@5b050000 (eth1) using random MAC address - 32:05:0c:f9:5e:10
, eth1: ethernet@5b050000
Hit any key to stop autoboot: 0

Signed-off-by: Oliver Graute <oliver.graute@kococonnector.com>