S2IO: Fixes for MSI and MSIX

- Added debug statements to print a debug message if the MSI/MSI-X vector (or)
  data is zero.

- This patch removes the code that will enable NAPI for the case of single
  ring and MSI-X / MSI case. There are some issue in the enabling NAPI with
  MSI/MSI-X.  So we are turning off NAPI in the case of MSI/MSI-X.

Signed-off-by: Sivakumar Subramani <sivakumar.subramani@neterion.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>