sfc: Use swap() instead of open coding it

stable inclusion
from stable-v5.10.117
commit bdb8d4aed1cf5054b7edc3edd402efd889d414bb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L66B

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bdb8d4aed1cf5054b7edc3edd402efd889d414bb



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[ Upstream commit 0cf765fb ]

Clean the following coccicheck warning:

./drivers/net/ethernet/sfc/efx_channels.c:870:36-37: WARNING opportunity
for swap().

./drivers/net/ethernet/sfc/efx_channels.c:824:36-37: WARNING opportunity
for swap().

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>