i40e: fix MSI-X vector redistribution if hw limit is reached

The driver allocates 1 vector per CPU thread and the current hardware
limit for vectors is 129 per PF. On systems with 128 or more threads
this currently means all vectors are used by the PF leaving no room for
additional features like VMDq, iWARP, etc...
The code that should redistribute the vectors in this case is broken and
never triggers. Fixed the code so that it actually triggers if the
hardware limit is reached and adjust the number of queue pairs
accordingly.
Also the number of initially requested iWARP vectors was not properly
saved when the vector limit was reached, and therefore always zero.

Comparison with debug statement.
Before:
i40e 0000:2d:00.0: VMDq disabled, not enough MSI-X vectors
i40e 0000:2d:00.0: IWARP disabled, not enough MSI-X vectors
i40e 00.0 MSI-X vector distribution: PF 128, VMDq 0, FDSB 0, iWARP 0
After:
i40e 0000:2d:00.0: MSI-X vector limit reached, attempting to redistribute vectors
i40e 00.0 MSI-X vector distribution: PF 78, VMDq 8, FDSB 0, iWARP 42

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>