ARM SSG/FM: Cope correctly with NC GPIO

Author: kjbracey

targets/TARGET_ARM_FM/TARGET_FVP_MPS2/gpio_api.c

@@ -27,11 +27,11 @@ uint32_t gpio_set(PinName pin)
 // with the object created for the pin
 void gpio_init(gpio_t *obj, PinName pin)
 {
+    obj->pin = pin;
     if (pin == NC) {
         return;
     } else {
         int pin_value = 0;
-        obj->pin = pin;
         if (pin <= 15) {
             pin_value = pin;
         } else if (pin >= 16 && pin <= 31) {

targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/gpio_api.c

@@ -101,6 +101,13 @@ void gpio_init(gpio_t *obj, PinName pin)
 {
     struct arm_gpio_dev_t *gpio_dev;
 
+    if (pin == NC) {
+        obj->pin_number = NC;
+        obj->gpio_dev = NULL;
+        obj->mps2_io_dev = NULL;
+        return;
+    }
+
     if (pin >= EXP0 && pin <= EXP51) {
         /* GPIO pins */
         switch (GPIO_DEV_NUMBER(pin)) {

targets/TARGET_ARM_SSG/TARGET_IOTSS/gpio_api.c

@@ -25,10 +25,10 @@ uint32_t gpio_set(PinName pin) {
 // this links the board control bits for each pin 
 // with the object created for the pin
 void gpio_init(gpio_t *obj, PinName pin) {
+        obj->pin = pin;
         if(pin == NC){ return;}
         else {
         int pin_value = 0;
-        obj->pin = pin;
         if(pin <=15){
             pin_value = pin;
         }else if (pin >= 16 && pin <= 31){