MFC r318382

MFC r318382
 1. Move Rx Processing to fp_taskqueue(). With this CPU utilization for
    processing interrupts drops to around 1% for 100G and under 1% for
    other speeds.
 2. Use sysctls for TRACE_LRO_CNT and TRACE_TSO_PKT_LEN
 3. remove unused mtx tx_lock
 4. bind taskqueue kernel thread to the appropriate cpu core
 5. when tx_ring is full, stop further transmits till at least 1/16th of
    the Tx Ring is empty. In our case 1K entries. Also if there are
    rx_pkts to process, put the taskqueue thread to sleep for 100ms,
    before enabling interrupts.
 6. Use rx_pkt_threshold of 128.

git-svn-id: svn://svn.freebsd.org/base/stable/10@318661 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f