frdm-kw41z: Define BTNx macros for user pushbuttons

boards/frdm-kw41z/include/board.h

@@ -53,6 +53,20 @@ extern "C"
 #define LED3_TOGGLE         (GPIOA->PTOR = LED3_MASK)
 /** @} */
 
+/**
+ * @name    Button pin definitions
+ * @{
+ */
+/* SW3, SW4 will short these pins to ground when pushed but there are no
+ * external pull resistors, use internal pull-ups on the pins */
+/* BTN0 is mapped to SW3 */
+#define BTN0_PIN            GPIO_PIN(PORT_C,  4)
+#define BTN0_MODE           GPIO_IN_PU
+/* BTN1 is mapped to SW4 */
+#define BTN1_PIN            GPIO_PIN(PORT_C,  5)
+#define BTN1_MODE           GPIO_IN_PU
+/** @} */
+
 /**
  * @name    xtimer configuration
  * @{

boards/frdm-kw41z/include/gpio_params.h

@@ -62,13 +62,13 @@ static const  saul_gpio_params_t saul_gpio_params[] =
     },
     {
         .name = "SW3",
-        .pin = GPIO_PIN(PORT_C, 4),
-        .mode = GPIO_IN_PU
+        .pin = BTN0_PIN,
+        .mode = BTN0_MODE,
     },
     {
         .name = "SW4",
-        .pin = GPIO_PIN(PORT_C, 5),
-        .mode = GPIO_IN_PU
+        .pin = BTN1_PIN,
+        .mode = BTN1_MODE,
     },
 };