qlcnic: Use shared interrupt vector for Tx and Rx

o VF will use shared MSI-X interrupt vector for Tx and Rx.
o When QLCNIC_INTR_SHARED flag is set Tx and Rx will
  share MSI-X interrupt vector. Tx will use a separate
  MSI-X interrupt vector from Rx otherwise.

Signed-off-by: Rajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>