[PATCH 2/3] drm/hisilicon/hibmc: Include <linux/io.h> for readl() and writel()

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Include <linux/io.h> to get readl() and writel() on S390. The error
message is shown below and a bug report is at [1].

  drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c:75:15: error: implicit declaration of function 'readl' [-Werror=implicit-function-declaration]
     75 |         reg = readl(priv->mmio + HIBMC_DISPLAY_CONTROL_HISILE);
        |               ^~~~~
  drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c:80:9: error: implicit declaration of function 'writel' [-Werror=implicit-function-declaration]
     80 |         writel(reg, priv->mmio + HIBMC_DISPLAY_CONTROL_HISILE);
	|         ^~~~~~

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Fixes: 45b64fd9f7ae ("drm/fb-helper: Remove unnecessary include statements")
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/dri-devel/202211060608.qrTg8b2E-lkp@xxxxxxxxx/T/#u # [1]
---
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
index c228091fb0e6a..8c6d2ea2a4729 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_vdac.c
@@ -11,6 +11,8 @@
  *	Jianhua Li <lijianhua@xxxxxxxxxx>
  */
 
+#include <linux/io.h>
+
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_print.h>
-- 
2.38.0