cpu/esp8266: doxygen fix

Removes architecture specific includes from documentation of module  Peripheral Driver Interface / GPIO.

cpu/esp8266/include/gpio_common.h

@@ -8,7 +8,6 @@
 
 /**
  * @ingroup     cpu_esp8266
- * @ingroup     drivers_periph_gpio
  * @{
  *
  * @file