media: venus: hfi: export few HFI functions

Export few HFI functions to use them from decoder to implement
more granular control needed for stateful Codec API compliance.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>