be2net: refactor code that decides adapter->num_rx_queues

The code has been refactored to not set num_rx_qs inside be_enable_msix().
num_rx_qs is now set at the time of queue creation based on the number of
available msix vectors.

Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>