drm/fb-helper: Set skip_panic if the drm driver supports drm panic

fb_info->skip_panic flag prevents fbcon from writing to the
framebuffer during a kernel panic. So set it when the drm driver
implements drm panic, to avoid overwriting the panic screen.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240717090102.968152-3-jfalempe@redhat.com