staging: mt7621-gpio: avoid including 'gpio.h'

Including file '<linux/gpio.h>' should be avoided in
new drivers code, so just remove it because it is
no necessary at all.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-gpio/gpio-mt7621.c

@@ -5,7 +5,6 @@
  */
 
 #include <linux/err.h>
-#include <linux/gpio.h>
 #include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>