net/smc: Add support for obtaining SMCD device list

mainline inclusion
from mainline-v5.11-rc1
commit aaf95523
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=aaf95523d5824ebc2c8c185a2de51063a750c446



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Deliver SMCD device information via netlink based
diagnostic interface.

Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Yingyu Zeng <zengyingyu@sangfor.com.cn>