bnxt_en: Reserve RDMA resources by default.

If the device supports RDMA, we'll setup network default rings so that
there are enough minimum resources for RDMA, if possible.  However, the
user can still increase network rings to the max if he wants.  The actual
RDMA resources won't be reserved until the RDMA driver registers.

v2: Fix compile warning when BNXT_CONFIG_SRIOV is not set.

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>