net/smc: Add netlink support for SMC statistics

mainline inclusion
from mainline-v5.14-rc1
commit 8c40602b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I78IFM
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=8c40602b4be17571dfd75102f4f1e690311c5210



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Add the netlink function which collects the statistics information and
delivers it to the userspace.

Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yingyu Zeng <zengyingyu@sangfor.com.cn>