net/mlx5e: Fix error path for ethtool set-priv-flag

stable inclusion
from stable-5.10.27
commit 08a5f812ad6c6a78a37fc6462bbee089a1342ed3
bugzilla: 51493

--------------------------------

[ Upstream commit 4eacfe72 ]

Expose error value when failing to comply to command:
$ ethtool --set-priv-flags eth2 rx_cqe_compress [on/off]

Fixes: be7e87f9 ("net/mlx5e: Fail safe cqe compressing/moderation mode setting")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by:   Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>