drm/amd/display: Check gpio_id before used as array index

[WHY & HOW]
GPIO_ID_UNKNOWN (-1) is not a valid value for array index and therefore
should be checked in advance.

This fixes 5 OVERRUN issues reported by Coverity.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/gpio/gpio_service.c

@@ -239,6 +239,9 @@ static bool is_pin_busy(
 	enum gpio_id id,
 	uint32_t en)
 {
+	if (id == GPIO_ID_UNKNOWN)
+		return false;
+
 	return service->busyness[id][en];
 }
 
@@ -247,6 +250,9 @@ static void set_pin_busy(
 	enum gpio_id id,
 	uint32_t en)
 {
+	if (id == GPIO_ID_UNKNOWN)
+		return;
+
 	service->busyness[id][en] = true;
 }
 
@@ -255,6 +261,9 @@ static void set_pin_free(
 	enum gpio_id id,
 	uint32_t en)
 {
+	if (id == GPIO_ID_UNKNOWN)
+		return;
+
 	service->busyness[id][en] = false;
 }
 
@@ -263,7 +272,7 @@ enum gpio_result dal_gpio_service_lock(
 	enum gpio_id id,
 	uint32_t en)
 {
-	if (!service->busyness[id]) {
+	if (id != GPIO_ID_UNKNOWN && !service->busyness[id]) {
 		ASSERT_CRITICAL(false);
 		return GPIO_RESULT_OPEN_FAILED;
 	}
@@ -277,7 +286,7 @@ enum gpio_result dal_gpio_service_unlock(
 	enum gpio_id id,
 	uint32_t en)
 {
-	if (!service->busyness[id]) {
+	if (id != GPIO_ID_UNKNOWN && !service->busyness[id]) {
 		ASSERT_CRITICAL(false);
 		return GPIO_RESULT_OPEN_FAILED;
 	}