eth: bnxt: handle invalid Tx completions more gracefully

Invalid Tx completions should never happen (tm) but when they do
they crash the host, because driver blindly trusts that there is
a valid skb pointer on the ring.

The completions I've seen appear to be some form of FW / HW
miscalculation or staleness, they have typical (small) values
(<100), but they are most often higher than number of queued
descriptors. They usually happen after boot.

Instead of crashing, print a warning and schedule a reset.

Link: https://lore.kernel.org/r/20230720010440.1967136-4-kuba@kernel.org


Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>