vxge: MSIX one shot mode

To reduce the possibility of losing an interrupt in the handler due to a
race between an interrupt processing and disable/enable of interrupts,
enable MSIX one shot.

Also, add support for adaptive interrupt coalesing

Signed-off-by: Jon Mason <jon.mason@exar.com>
Signed-off-by: Masroor Vettuparambil <masroor.vettuparambil@exar.com>
Signed-off-by: David S. Miller <davem@davemloft.net>