acl-plugin: add hitcount to applied hash-acl entries

Add a counter incremented upon the ACL check,
so it is easier to see which kind of traffic
is being checked by the policy, add the corresponding
output to the debug CLI "show acl-plugin tables" command.

Change-Id: Id811dddf204e63eeceabfcc509e3e9c5aae1dbc8
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>