greybus: arche-platform: fix incorrect gpio variable type

GPIO number obtained from of_get_named_gpio() should be signed to allow
error handling.

Testing Done:
Built & booted on EVT1.5
Signed-off-by: David Lin <dtwlin@google.com>
Reviewed-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/arche-apb-ctrl.c

@@ -37,7 +37,7 @@ struct arche_apb_ctrl_drvdata {
 	struct regulator *vcore;
 	struct regulator *vio;
 
-	unsigned int clk_en_gpio;
+	int clk_en_gpio;
 	struct clk *clk;
 
 	struct pinctrl *pinctrl;

drivers/staging/greybus/arche-platform.c

@@ -44,7 +44,7 @@ struct arche_platform_drvdata {
 
 	enum arche_platform_state state;
 
-	unsigned int svc_refclk_req;
+	int svc_refclk_req;
 	struct clk *svc_ref_clk;
 
 	struct pinctrl *pinctrl;