ethernet: atheros: fix return value check in atl1e_tso_csum()

ethernet: atheros: fix return value check in atl1e_tso_csum()

in atl1e_tso_csum, it should check the return value of pskb_trim(),
and return an error code if an unexpected value is returned
by pskb_trim().

Fixes: a6a5325239c2 ("atl1e: Atheros L1E Gigabit Ethernet driver")
Signed-off-by: Yuanjun Gong <ruc_gongyuanjun@163.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230720144219.39285-1-ruc_gongyuanjun@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>