Add bus_release_resource() method to nexus on arm64
The nexus module was missing method for releasing bus resources. As a
result, it couldn't be released and the bus_release_resource() call would
Next call to bus_alloc_resource() for the same resource was returning
error, because it wasn't released previously and it was still busy.
The implementation of the nexus_release_resource() is the same as for
Submitted by: Michal Krawczyk <email@example.com>
Reported-by: Greg V <firstname.lastname@example.org>
Tested-by: cperciva, Greg V <email@example.com>
Obtained from: Semihalf
MFC after: 2 weeks
Sponsored by: Amazon, Inc.
Differential revision: https://reviews.freebsd.org/D19641