We are targeting let uboot loading images from emmc to boot android.
Currently only emmc1 is enabled, so other devices are disabled.

Also change memory layout according to VM layout. The memory layout
needs to be samesize as what you configured in as "memory = "3584"".

Add a new dts dedicated for this kind uboot, add a new defconfig
to select CONFIG_XEN/CONFIG_XEN_DEBUG_SERIAL, deselect CONFIG_DM_SERIAL,
select CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK, and disable some devices
compared with imx8qm_mek_androidauto_defconfig.

Signed-off-by: Peng Fan <peng.fan@nxp.com>