gpio: Add a function to get a pin number from mraa_gpio_context

Signed-off-by: Kenta Yonekura <yoneken@ieee.org>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/gpio/gpio.c

@@ -573,3 +573,9 @@ mraa_gpio_use_mmaped(mraa_gpio_context dev, mraa_boolean_t mmap_en)
     syslog(LOG_ERR, "gpio: mmap not implemented on this platform");
     return MRAA_ERROR_FEATURE_NOT_IMPLEMENTED;
 }
+
+int
+mraa_gpio_get_pin(mraa_gpio_context dev)
+{
+    return dev->phy_pin;
+}