Remove drm_fb_cma_fbdev_init_with_funcs(), its only user tinydrm has
moved to drm_fbdev_generic_setup().

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: David Lechner <david@lechnology.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180703160354.59955-9-noralf@tronnes.org