net: hns3: minor refactor related to desc_cb handling

mainline inclusion
from mainline-master
commit 26f1ccdf
category: feature
bugzilla: 173966
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=26f1ccdf609a9fb087f49a3782fdc2ade23cde82



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desc_cb is used to store mapping and freeing info for the
corresponding desc, which is used in the cleaning process.
There will be more desc_cb type coming up when supporting the
tx bounce buffer, change desc_cb type to bit-wise value in order
to reduce the desc_cb type checking operation in the data path.

Also move the desc_cb type definition to hns3_enet.h because it
is only used in hns3_enet.c, and declare a local variable desc_cb
in hns3_clear_desc() to reduce lines of code.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>