staging:r8188eu: replace recv_frame->rx_(data|len|tail) with pkt->(data|len|tail) and remove unused recvframe_(put|pull|pull_tail)()

recv_frame->rx_(data|len|tail) duplicate pkt (skb) data|len|tail members
and require special functions recvframe_(put|pull|pull_tail)()
instead of skb_(put|pull|trim).
Replace rx_(data|len|tail) with pkt->(data|len|tail),
remove rx_(data|len|tail) and remove recvframe_(put|pull|pull_tail)().
Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>