net/smc: Add connection counters for links

mainline inclusion
from mainline-v5.11-rc1
commit 07d51580
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I79GVV
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=07d51580ff6594dc7261821ee40b37392040db2a



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Add connection counters to the structure of the link.
Increase/decrease the counters as needed in the corresponding
routines.

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: Gengbiao Shen <shengengbiao@sangfor.com.cn>