staging: wilc1000: Include linux/gpio.h instead of asm/gpio.h

Fix:

drivers/staging/wilc1000/linux_wlan.c:18:22: fatal error:
	asm/gpio.h: No such file or directory

Not every architecture has asm/gpio.h. Include linux/gpio.h instead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>