drm/kmb: Enable support for framebuffer console

Enable support for fbcon (framebuffer console).

v2: added missing static clk_enable
v3: removed module parameter, use fbdev_emulation instead. Use
preferred depth of 24 for color depth. (Thomas Z.)
Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211019230719.789958-2-anitha.chrisanthus@intel.com

drivers/gpu/drm/kmb/kmb_drv.c

@@ -15,6 +15,7 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_probe_helper.h>
@@ -176,6 +177,7 @@ static int kmb_setup_mode_config(struct drm_device *drm)
 	drm->mode_config.min_height = KMB_MIN_HEIGHT;
 	drm->mode_config.max_width = KMB_MAX_WIDTH;
 	drm->mode_config.max_height = KMB_MAX_HEIGHT;
+	drm->mode_config.preferred_depth = 24;
 	drm->mode_config.funcs = &kmb_mode_config_funcs;
 
 	ret = kmb_setup_crtc(drm);
@@ -559,6 +561,8 @@ static int kmb_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_register;
 
+	drm_fbdev_generic_setup(&kmb->drm, 0);
+
 	return 0;
 
  err_register: