drm/client: Don't add new command-line mode

Don't add a mode for the kernel's command-line parameters from
within the DRM client code. Doing so can result in an unusable
display. If there's no compatible command-line mode, the client
will use one of the connector's preferred modes.

All mode creation and validation has to be performed by the
connector. When clients run, the connector's fill_modes callback
has already processed the kernel parameters and validated each
mode before adding it. The connector's mode list does not contain
invalid modes.

v2:
	* grammar in commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220511183125.14294-4-tzimmermann@suse.de