drm/msm: dsi: fix compile errors when CONFIG_GPIOLIB=n

drm/msm: dsi: fix compile errors when CONFIG_GPIOLIB=n

I'm not sure where, exactly, but somewhere in here we must be relying on
an implicit include.

drivers/gpu/drm/msm/dsi/dsi_host.c: In function ‘dsi_host_init_panel_gpios’:
drivers/gpu/drm/msm/dsi/dsi_host.c:1356:2: error: implicit declaration of function ‘devm_gpiod_get’ [-Werror=implicit-function-declaration]
  msm_host->disp_en_gpio = devm_gpiod_get(panel_device,
  ^
drivers/gpu/drm/msm/dsi/dsi_host.c:1356:25: warning: assignment makes pointer from integer without a cast [enabled by default]
  msm_host->disp_en_gpio = devm_gpiod_get(panel_device,
                         ^
drivers/gpu/drm/msm/dsi/dsi_host.c:1364:3: error: implicit declaration of function ‘gpiod_direction_output’ [-Werror=implicit-function-declaration]
   ret = gpiod_direction_output(msm_host->disp_en_gpio, 0);
   ^
drivers/gpu/drm/msm/dsi/dsi_host.c:1371:20: warning: assignment makes pointer from integer without a cast [enabled by default]
  msm_host->te_gpio = devm_gpiod_get(panel_device, "disp-te");
                    ^
drivers/gpu/drm/msm/dsi/dsi_host.c:1378:3: error: implicit declaration of function ‘gpiod_direction_input’ [-Werror=implicit-function-declaration]
   ret = gpiod_direction_input(msm_host->te_gpio);
   ^
drivers/gpu/drm/msm/dsi/dsi_host.c: In function ‘msm_dsi_host_power_on’:
drivers/gpu/drm/msm/dsi/dsi_host.c:1918:3: error: implicit declaration of function ‘gpiod_set_value’ [-Werror=implicit-function-declaration]
   gpiod_set_value(msm_host->disp_en_gpio, 1);
   ^

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Hai Li <hali@codeaurora.org>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Rob Clark <robdclark@gmail.com>