drm/tegra: Use regular fbdev I/O helpers

Use the regular fbdev helpers for framebuffer I/O instead of DRM's
helpers. Tegra does not use damage handling, so DRM's fbdev helpers
are mere wrappers around the fbdev code.

By using fbdev helpers directly within each DRM fbdev emulation,
we can eventually remove DRM's wrapper functions entirely.

v4:
	* use initializer macros for struct fb_ops
v2:
	* use FB_SYS_HELPERS option

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Mikko Perttunen <mperttunen@nvidia.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230530151228.22979-10-tzimmermann@suse.de

drivers/gpu/drm/tegra/Kconfig

@@ -12,6 +12,7 @@ config DRM_TEGRA
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL
+	select FB_SYS_HELPERS if DRM_FBDEV_EMULATION
 	select TEGRA_HOST1X
 	select INTERCONNECT
 	select IOMMU_IOVA

drivers/gpu/drm/tegra/fbdev.c

@@ -8,6 +8,7 @@
  */
 
 #include <linux/console.h>
+#include <linux/fb.h>
 #include <linux/vmalloc.h>
 
 #include <drm/drm_drv.h>
@@ -58,12 +59,9 @@ static void tegra_fbdev_fb_destroy(struct fb_info *info)
 
 static const struct fb_ops tegra_fb_ops = {
 	.owner = THIS_MODULE,
+	__FB_DEFAULT_SYS_OPS_RDWR,
 	DRM_FB_HELPER_DEFAULT_OPS,
-	.fb_read = drm_fb_helper_sys_read,
-	.fb_write = drm_fb_helper_sys_write,
-	.fb_fillrect = drm_fb_helper_sys_fillrect,
-	.fb_copyarea = drm_fb_helper_sys_copyarea,
-	.fb_imageblit = drm_fb_helper_sys_imageblit,
+	__FB_DEFAULT_SYS_OPS_DRAW,
 	.fb_mmap = tegra_fb_mmap,
 	.fb_destroy = tegra_fbdev_fb_destroy,
 };