scsi: storvsc: Parameterize number hardware queues

scsi: storvsc: Parameterize number hardware queues

Add ability to set the number of hardware queues with new module parameter,
storvsc_max_hw_queues. The default value remains the number of CPUs.  This
functionality is useful in some environments (e.g. Microsoft Azure) where
decreasing the number of hardware queues has been shown to improve
performance.

Link: https://lore.kernel.org/r/20210224232948.4651-1-melanieplageman@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Melanie Plageman (Microsoft) <melanieplageman@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>