This patch adds support of dumping MAC umv counter in debugfs,
which will be helpful for debugging.

The display style is below:
$ cat umv_info
num_alloc_vport  : 2
max_umv_size     : 256
wanted_umv_size  : 256
priv_umv_size    : 85
share_umv_size   : 86
vport(0) used_umv_num : 1
vport(1) used_umv_num : 1
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>