net/smc: Add netlink support for SMC fallback statistics

mainline inclusion
from mainline-v5.14-rc1
commit f0dd7bf5
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=f0dd7bf5e33066e554442c509ef6351728b95b51



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

Add support to collect more detailed SMC fallback reason statistics and
provide these statistics to user space on the netlink interface.

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>