drm/arm/hdlcd: remove calls to drm_mode_config_cleanup()

drm_mode_config_init() simply calls drmm_mode_config_init(), hence
cleanup is automatically handled through registering
drm_mode_config_cleanup() with drmm_add_action_or_reset().

While at it, get rid of the deprecated drm_mode_config_init() and
replace it with drmm_mode_config_init() directly.

Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026153431.72033-5-dakr@redhat.com