bnxt_en: Implement RX ring reset in response to buffer errors.

On some older chips, it is necessary to do a reset when we get buffer
errors associated with an RX ring.  These buffer errors may become
frequent if the RX ring underruns under heavy traffic.  The current
code does a global reset of all reasources when this happens.  This
works but creates a big disruption of all rings when one RX ring is
having problem.  This patch implements a localized RX ring reset of
just the RX ring having the issue.  All other rings including all
TX rings will not be affected by this single RX ring reset.

Only the older chips prior to the P5 class supports this reset.
Because it is not a global reset, packets may still be arriving
while we are calling firmware to reset that ring.  We need to be
sure that we don't post any buffers during this time while the
ring is undergoing reset.  After firmware completes successfully,
the ring will be in the reset state with no buffers and we can start
filling it with new buffers and posting them.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>