acl-plugin: refactor to introduce multiarch dataplane functions

acl-plugin: refactor to introduce multiarch dataplane functions

This commit splits the functions from fa_node.c
into the pure dataplane node functions (which are multiarch-compiled),
session management node functions (which are compiled only once),
and session find/add/delete functions which are split out into the inlines.

As part of the refactoring:

- get rid of BV() macros in the affected chunk of code,
  rather use the explicit bihash function names.

- add the magic trailer to the new files to
  ensure make checkstyle watches them.

- move the bihash_template.c include for 40_8 bihash into acl.c

Change-Id: I4d781e9ec4307ea84e92af93c09470ea2bd0c375
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>