drm/plane: Move range check for format_count earlier

In the Linux kernel, the following vulnerability has been resolved:

drm/plane: Move range check for format_count earlier

While the check for format_count > 64 in __drm_universal_plane_init()

shouldn't be hit (it's a WARN_ON), in its current position it will then

leak the plane->format_types array and fail to call

drm_mode_object_unregister() leaking the modeset identifier. Move it to

the start of the function to avoid allocating those resources in the

first place.