ARM: imx: Enable SPL GPIO hog on i.MX8M Plus DHCOM

Enable GPIO hog support in SPL to match the GPIO hog support in U-Boot proper.

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