fix copy in regenerate-files script (#194)

As in the original regenerate-files script from
https://github.com/openconfig/gnsi/pull/37/files#diff-fc93ffaaee0a108cd0141877980a22c2c5f782b529e4561cd11243753b91eed8
the copy should be from
"${BASE}"/"${pkg}"/"${proto}"_go_proto_/"${GNOI_NS}"/"${pkg}"/*.pb.go
to
the target package
rather than the
"${BASE}"/"${pkg}"/"${proto}"_go_proto_/"${GNOI_NS}"/"${proto}"/*.pb.go
which was in the base patch
e.g. the files for packet link qualification will be under
linkqual_go_proto_/github.com/openconfig/gnoi/packet_link_qualification/packet_link_qualification.pb.go

Author: brianneville