VPP-574: fix the MACIP ACLs blocking ARP traffic

VPP-574: fix the MACIP ACLs blocking ARP traffic

The initial assumption was that the MACIP ACL classifier tables would be applied
after the classification of the traffic based on the ethertype, it turned out
to be untrue, but the fix in the code did not happen.

Add the ethertype to the mask, and the logic to create the ACL classifier tables
permitting the ARP ethertype with the correct payload.

Change-Id: I70236a8a723970c662ddaef6bc9fce93d2e630c1
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>