77cae244f8
during detach() similar to other NIC drivers rather than allocating them during init() and freeing them during stop(): - Move creation of tx bus_dma tag amd maps and tx_buffer_area from em_setup_transmit_structures() to em_allocate_transmit_structures(). - Call em_allocate_xxx_structures() in em_attach(). - Only call em_free_xxx_structures() in em_detach(). - Change em_setup_xxx_structures() to free any existing tx or rx buffers and in the case of rx repopulate the ring with newer buffers. Reviewed by: jfv