regulator: bd70528: Drop unused include

This driver does not use any symbols from <linux/gpio.h>
so just drop the include.

Cc: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-By: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/bd70528-regulator.c

@@ -4,7 +4,6 @@
 
 #include <linux/delay.h>
 #include <linux/err.h>
-#include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/mfd/rohm-bd70528.h>