libnetwork: macvlan: processIPAM(): simplify
libnetwork: macvlan: processIPAM(): simplify

Remove redundant checks and intermediate variables.

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

nawawi/docker,trebonian/docker,cpuguy83/docker,Mokolea/docker,Mokolea/docker,moul/docker,Ramzec/docker,konstruktoid/docker-upstream,moby/moby,nawawi/docker,cpuguy83/docker,Ramzec/docker,thaJeztah/docker,moby/moby,cpuguy83/docker,Ramzec/docker,thaJeztah/docker,jimjag/docker,mahak/docker,nawawi/docker,jimjag/docker,moul/docker,Mokolea/docker,Mokolea/docker,moby/moby,trebonian/docker,trebonian/docker,mahak/docker,jimjag/docker,Ramzec/docker,moby/moby,moul/docker,thaJeztah/docker,nawawi/docker,mahak/docker,trebonian/docker,moul/docker,mahak/docker,konstruktoid/docker-upstream,cpuguy83/docker,konstruktoid/docker-upstream,jimjag/docker,konstruktoid/docker-upstream,thaJeztah/docker