net: hns3: PF supports to set and query lane_num by sysfs

driver inclusion
category:feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I62HX2



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

When serdes lane support setting 25Gb/s、50Gb/s speed and user wants to
set port speed as 50Gb/s, it can be setted as one 50Gb/s serdes lane or
two 25Gb/s serdes lanes.

So, this patch adds support to query and set lane number by sysfs
to satisfy this scenario.

Signed-off-by: Hao Chen <chenhao418@huawei.com>
Signed-off-by: Jiantao Xiao <xiaojiantao1@h-partners.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>