[PATCH] drm/msm/dp: add linux/io.h header to fix build errors

[Randy Dunlap]

Add <linux/io.h> header to pull in readl/writel and friends.
This eliminates the following build errors:

drivers/gpu/drm/msm/dp/dp_panel.c: In function 'msm_dp_read_link':
drivers/gpu/drm/msm/dp/dp_panel.c:33:16: error: implicit declaration of function 'readl_relaxed' [-Wimplicit-function-declaration]
   33 |         return readl_relaxed(panel->link_base + offset);
drivers/gpu/drm/msm/dp/dp_panel.c: In function 'msm_dp_write_link':
drivers/gpu/drm/msm/dp/dp_panel.c:43:9: error: implicit declaration of function 'writel' [-Wimplicit-function-declaration]
   43 |         writel(data, panel->link_base + offset);

Fixes: d7e3bee925bd ("drm/msm/dp: drop the msm_dp_catalog module")
Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Cc: Stephen Boyd <swboyd at chromium.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>
Cc: Dmitry Baryshkov <lumag at kernel.org>
Cc: Rob Clark <robin.clark at oss.qualcomm.com>
Cc: linux-arm-msm at vger.kernel.org
Cc: freedreno at lists.freedesktop.org
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/msm/dp/dp_panel.c |    2 ++
 1 file changed, 2 insertions(+)

--- linux-next-20250617.orig/drivers/gpu/drm/msm/dp/dp_panel.c
+++ linux-next-20250617/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -12,6 +12,8 @@
 #include <drm/drm_of.h>
 #include <drm/drm_print.h>
 
+#include <linux/io.h>
+
 #define DP_INTF_CONFIG_DATABUS_WIDEN     BIT(4)
 
 #define DP_MAX_NUM_DP_LANES	4