net/i40e: determine number of queues per VF at run time

net/i40e: determine number of queues per VF at run time

Without this patch, the number of queues per i40e VF is set to 4
by CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_VF=4 in config/common_base.
It is a fixed value determined at compile time and can't be changed
at run time.
With this patch, the number of queues per i40e VF can be determined
at run time. For example, if the PCI address of an i40e PF is
aaaa:bb.cc, with the EAL parameter -w aaaa:bb.cc,queue-num-per-vf=8,
the number of queues per VF created from this PF is set to 8.
If there is no "queue-num-per-vf" setting in EAL parameters, it uses
the default value of 4. And if the value after the "queue-num-per-vf"
is invalid, it will also use the default value. The valid values can
be 1, 2, 4, 8, or 16.

Signed-off-by: Wei Dai <wei.dai@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>