qlcnic: Allow setting TX interrupt coalescing parameters from VF.

o Tx interrupt coalescing parameters can now be set from VF.
o Added validation code in PF to validate the parameters.

Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>