bnxt_en: Restore PTP tx_avail count in case of skb_pad() error

[ Upstream commit 1e796211 ]

The current code only restores PTP tx_avail count when we get DMA
mapping errors.  Fix it so that the PTP tx_avail count will be
restored for both DMA mapping errors and skb_pad() errors.
Otherwise PTP TX timestamp will not be available after a PTP
packet hits the skb_pad() error.

Fixes: 83bb623c

 ("bnxt_en: Transmit and retrieve packet timestamps")
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240618215313.29631-4-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>