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>
diff --git a/configs/imx8mm_venice_defconfig b/configs/imx8mm_venice_defconfig
index 09f7d8a..b596f7e 100644
--- a/configs/imx8mm_venice_defconfig
+++ b/configs/imx8mm_venice_defconfig
@@ -73,6 +73,7 @@
 CONFIG_CLK_COMPOSITE_CCF=y
 CONFIG_SPL_CLK_IMX8MM=y
 CONFIG_CLK_IMX8MM=y
+CONFIG_GPIO_HOG=y
 CONFIG_MXC_GPIO=y
 CONFIG_DM_I2C=y
 CONFIG_LED=y