ipu-v3: Include <linux/io.h>

The code uses readl() and writel(). Include the header file to
get the declarations.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20230512102444.5438-4-tzimmermann@suse.de

drivers/gpu/ipu-v3/ipu-prv.h

@@ -8,6 +8,7 @@
 
 struct ipu_soc;
 
+#include <linux/io.h>
 #include <linux/types.h>
 #include <linux/device.h>
 #include <linux/clk.h>