drm/mgag200: Remove special case for G200SE with <2 MiB

Remove old test for 32-bit vs 16-bit colors. Prefer 24-bit color depth
on all devices. 32-bit color depth doesn't exist, it should have always
been 24-bit.

G200SE with less than 2 MiB of video memory have defaulted to 16-bit
color depth, as the original revision of the G200SE had only 1.75 MiB
of video memory. Using 16-bit colors enabled XGA resolution. But we
now already limit these devices to VGA resolutions as the memory-bandwith
test assumes 32-bit pixel size. So drop the special case from color-depth
selection.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220601112522.5774-2-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -1072,14 +1072,6 @@ static const struct drm_mode_config_funcs mgag200_mode_config_funcs = {
 	.atomic_commit = drm_atomic_helper_commit,
 };
 
-static unsigned int mgag200_preferred_depth(struct mga_device *mdev)
-{
-	if (IS_G200_SE(mdev) && mdev->vram_fb_available < (2048*1024))
-		return 16;
-	else
-		return 32;
-}
-
 int mgag200_modeset_init(struct mga_device *mdev)
 {
 	struct drm_device *dev = &mdev->base;
@@ -1100,11 +1092,8 @@ int mgag200_modeset_init(struct mga_device *mdev)
 
 	dev->mode_config.max_width = MGAG200_MAX_FB_WIDTH;
 	dev->mode_config.max_height = MGAG200_MAX_FB_HEIGHT;
-
-	dev->mode_config.preferred_depth = mgag200_preferred_depth(mdev);
-
+	dev->mode_config.preferred_depth = 24;
 	dev->mode_config.fb_base = mdev->mc.vram_base;
-
 	dev->mode_config.funcs = &mgag200_mode_config_funcs;
 
 	ret = mgag200_i2c_init(mdev, i2c);