net: ipa: extend endpoints in packet init command

The IP_PACKET_INIT immediate command defines the destination
endpoint to which a packet should be sent.  Prior to IPA v5.0, a
5 bit field in that command represents the endpoint, but starting
with IPA v5.0, the field is extended to 8 bits to support more than
32 endpoints.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>