drm/bridge: ps8622: Include linux/gpio/consumer.h

If GPIOLIB=n and asm-generic/gpio.h is not used:

    drivers/gpu/drm/bridge/ps8622.c: In function ‘ps8622_pre_enable’:
    drivers/gpu/drm/bridge/ps8622.c:368: error: implicit declaration of function ‘gpiod_set_value’
    drivers/gpu/drm/bridge/ps8622.c: In function ‘ps8622_probe’:
    drivers/gpu/drm/bridge/ps8622.c:584: error: implicit declaration of function ‘devm_gpiod_get’
    drivers/gpu/drm/bridge/ps8622.c:584: warning: assignment makes pointer from integer without a cast
    drivers/gpu/drm/bridge/ps8622.c:590: error: implicit declaration of function ‘gpiod_direction_output’
    drivers/gpu/drm/bridge/ps8622.c:596: warning: assignment makes pointer from integer without a cast

Add the missing #include <linux/gpio/consumer.h> to fix this.

Fixes: f1336e6afb ("drm/bridge: Add I2C based driver for ps8622/ps8625 bridge")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Thierry Reding <treding@nvidia.com>