net: wangxun: add ethtool_ops for channel number

Add support to get RX/TX queue number with ethtool -l, and set RX/TX
queue number with ethtool -L. Since interrupts need to be rescheduled,
adjust the allocation of msix enties.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>