mfd: menelaus: Remove unused linux/gpio.h

linux/gpio.h is deprecated and subject to remove.
The driver doesn't use it, simply remove the unused header.

Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/menelaus.c

···
 #include <linux/bcd.h>
 #include <linux/slab.h>
 #include <linux/mfd/menelaus.h>
-#include <linux/gpio.h>
 
 #include <asm/mach/irq.h>