ofp-actions: Make ofpacts_check() report consistency for all protocols.

Until now ofpacts_check() has been told either to enforce consistency or
not, but that means that the caller has to know exactly what protocol is
going to be in use (because some protocols require consistency to be
enforced and others don't).  This commit changes ofpacts_check() to just
rule out protocols that require enforcement when it detects
inconsistencies.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>