regulator: rpi-panel-attiny: Drop useless header

The RPI panel regulator driver includes the legacy header
<linux/gpio.h> for no reason, this is a driver and <linux/gpio/driver.h>
is already included. Drop the include.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230808-descriptors-regulator-v1-3-939b5e84dd18@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/rpi-panel-attiny-regulator.c

@@ -7,7 +7,6 @@
 
 #include <linux/backlight.h>
 #include <linux/err.h>
-#include <linux/gpio.h>
 #include <linux/gpio/driver.h>
 #include <linux/i2c.h>
 #include <linux/init.h>