[th/fedora-22-wifi-mac-addr-conf] contrib/rpm: rename section in "22-wifi-mac-addr.conf"

For [connection*] and [device*] sections, any suffix is allowed in
the group.

However (at least for configuration snippets we ship upstream), we
want to give a suffix that matches the name of the configuration
snippet.

It seems more common to use [connection-*] instead of [connection.].
See also "examples/nm-conf.d/*.conf" and "15-carrier-timeout.conf" file
which contains a [device-15-carrier-timeout] section.

Note that this file (in Fedora) is not configuration (installed in
/usr/lib). It is thus not problematic to modify.

Fixes: ea8dbd7a6d0f ('contrib/rpm: add "22-wifi-mac-addr.conf" to F40+')