ARM: dts: imx8m: imx8mm-mx8menlo: Enable SPL SDP support

ARM: dts: imx8m: imx8mm-mx8menlo: Enable SPL SDP support

Enable DM USB, DM PHY and USB gadget support in imx8mm-mx8menlo SPL
to let the board continue SDP loading of second stage after the first
stage was loaded by BootROM SDP implementation. It is not possible to
jump back into BootROM v1 and let the BootROM implementation continue
the SDP loading, all this has to be performed by the U-Boot CI HDRC
controller driver and SDP protocol implementation, both of which fit
into the SPL just barely.

With this patch, it is possible to start both U-Boot SPL and U-Boot
using e.g. uuu on this board as follows:

$ uuu -brun spl flash.bin

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>