vl: add entry point

vl: add entry point

Add entrypoint to distinguish H.264 decode and encode. For example, in patch
5/11 when is calling "VaCreateContext", "pps" and "sps" shouldn't be allocated
for H.264 encoding. So we need to use the entry_point to determine this is
H.264 decode or H.264 encode. We can use config to determine the entrypoint
since config_id is passed to us for VaCreateContext call. However, for
VaDestoyContext call, only context_id is passed to us. So we need to know the
entrypoint in order to not free the pps/sps for encoding case.

Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>