drivers: wifi: esp: access socket type and ip_proto from net_context

net_context contains both net_sock_type and net_ip_protocol, which are
static during the lifetime of net_context. net_context has basically the
ownership of esp_socket, so we can be sure 'type' and 'ip_proto' are
always accessible through net_context API.

Remove 'type' and 'ip_proto' members from 'esp_socket' structure, as
those are already accessible by net_context API.

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>