be2net: Request RSS capability of Rx interface depending on number of Rx rings

Currently we request RSS capability even if a single Rx ring is created.
As a result in few cases we unnecessarily consume an RSS capable interface
which is a limited resource in the chip.
This patch enables RSS on an interface only if more than one Rx ring
is created.

Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>