Using anv_pipeline_cache_upload_kernel() will re-upload the kernel and
prog_data when we merge caches. Since the kernel and prog_data is
already in the program_stream, use anv_pipeline_cache_add_entry()
instead to only add the entry to the hash table.
This function is a helper that unconditionally sets a hash table entry
and expects the cache to have enough room. Calling it 'add_entry'
suggests it will grow the cache as needed.
We can serialize as much as the application asks for and just stop once
we run out of memory. This lets applications use a fixed amount of
space for caching and still get some benefit.
