arm: dts: imx8m*-venice: add gpio hog support

arm: dts: imx8m*-venice: add gpio hog support

Add gpio hog support for board-specific gpio lines:
- put hogs in u-boot.dtsi so as to keep the regular dts files
  in sync with the kernel. The hogs will not be put in the kernel
  as that makes them un-usable by userspace as well as
  re-initializes them to dt defaults overriding changes which may
  have been done by bootloader commands.
- specify gpio names and initial config
- enable GPIO_HOG

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Peng Fan <peng.fan@nxp.com>