eth: bnxt: fix missing ring index trim on error path

Commit under Fixes converted tx_prod to be free running but missed
masking it on the Tx error path. This crashes on error conditions,
for example when DMA mapping fails.

Fixes: 6d1add95 ("bnxt_en: Modify TX ring indexing logic.")
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250414143210.458625-1-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>