regulator: mt6311: Drop useless header

The mt6311 includes the legacy header <linux/gpio.h> for no
reason, drop the include.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230808-descriptors-regulator-v1-6-939b5e84dd18@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mt6311-regulator.c

@@ -4,7 +4,6 @@
 // Author: Henry Chen <henryc.chen@mediatek.com>
 
 #include <linux/err.h>
-#include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>