drm/bridge: lt8912b: Drop unused includes

The Lontium bridge is including legacy header files for GPIO
but not using them. Delete the includes.

Cc: Adrien Grassein <adrien.grassein@gmail.com>
Cc: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Adren Grassein <adrien.grassein@gmail.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210529002759.468964-1-linus.walleij@linaro.org

drivers/gpu/drm/bridge/lontium-lt8912b.c

@@ -7,8 +7,6 @@
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
-#include <linux/gpio.h>
-#include <linux/of_gpio.h>
 #include <linux/regmap.h>
 
 #include <drm/drm_probe_helper.h>