bsp/lpc24xx: Add lpc24xx_pin_get_first_index()

c/src/lib/libbsp/arm/lpc24xx/include/io.h

@@ -294,6 +294,16 @@ rtems_status_code lpc24xx_pin_config(
   lpc24xx_pin_action action
 );
 
+/**
+ * @brief Returns the first pin index of a pin range.
+ */
+static inline unsigned lpc24xx_pin_get_first_index(
+  const lpc24xx_pin_range *range
+)
+{
+  return LPC24XX_IO_INDEX_BY_PORT(range->fields.port, range->fields.port_bit);
+}
+
 /**
  * @name ADC Pins
  *