gpio: Enable hogging support in SPL

Use the CONFIG macros to conditionally build the GPIO hogging support in
either the SPL or U-Boot, or both, depending on the configuration. Also
call the GPIO hog probe function in the common SPL board initialization
as an equivalent to adding it to the U-Boot init sequence functions.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index a55e368..89068c7 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -57,6 +57,15 @@
 	  is a mechanism providing automatic GPIO request and config-
 	  uration as part of the gpio-controller's driver probe function.
 
+config SPL_GPIO_HOG
+	bool "Enable GPIO hog support in SPL"
+	depends on SPL_GPIO_SUPPORT
+	help
+	  Enable gpio hog support in SPL
+	  The GPIO chip may contain GPIO hog definitions. GPIO hogging
+	  is a mechanism providing automatic GPIO request and config-
+	  uration as part of the gpio-controller's driver probe function.
+
 config DM_GPIO_LOOKUP_LABEL
 	bool "Enable searching for gpio labelnames"
 	depends on DM_GPIO