drm/xen: remove redundant initialization info print

drm_dev_register() already prints the same information on successful
init. Remove the redundant prints.

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Acked-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Acked-by: Simon Ser <contact@emersion.fr>
Link: https://patchwork.freedesktop.org/patch/msgid/900b3836c80a23923ede034ab10eb344be1e35bd.1733322525.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>