bnxt_en: Refactor bnxt_free_tx_rings() to free per TX ring

Modify bnxt_free_tx_rings() to free the skbs per TX ring.
This will be useful later in the series.

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250213011240.1640031-6-michael.chan@broadcom.com


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