Convert the following uses:

netbt/l2cap_socket.c:           m = m_get(M_NOWAIT, MT_DATA);
netbt/rfcomm_socket.c:          m = m_get(M_WAITOK, MT_DATA);
netbt/sco_socket.c:             m = m_get(MB_WAIT, MT_DATA);
netbt/sco_socket.c:             m = m_get(M_WAITOK, MT_DATA);

Sizes must be programatically determined for the first argument to m_getb, if it is non-obvious a comment should be added above the call to m_getb briefly explaining what is to be put into the mbuf.