Export clock required for RPiVid video decoder hardware.

Cc: Dom Cobley <popcornmix@gmail.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Ivan T. Ivanov <iivanov@suse.de>
Link: https://lore.kernel.org/r/20220829152154.147250-2-iivanov@suse.deSigned-off-by: Stephen Boyd <sboyd@kernel.org>