Merge pull request #5315 from bapclenet/samd21/gpio_PA27

SAMD21/GPIO driver: Add missing interrupts

cpu/samd21/periph/gpio.c

@@ -44,9 +44,9 @@
  */
 static const int8_t exti_config[2][32] = {
     {-1,  1, -1, -1,  4,  5,  6,  7, -1,  9, 10, 11, 12, 13, 14, 15,
-     -1,  1,  2,  3, -1, -1,  6,  7, 12, 13, -1, -1,  8, -1, -1, -1},
+     -1,  1,  2,  3, -1, -1,  6,  7, 12, 13, -1, 15,  8, -1, 10, 11},
     { 0, -1,  2,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-      0,  1, -1, -1, -1, -1,  6,  7, -1, -1, -1, 15,  8, -1, 10, 11},
+      0,  1, -1, -1, -1, -1,  6,  7, -1, -1, -1,  0,  8, -1, -1, -1},
 };
 
 /**