meta-systemd: Append ${PN} to SYSTEMD_SERVICE

When using systemd class from OE-Core we also need
to install the units explicitly.

systemd packages ending with -systemd are consumed
and now provided by package proper.

MJ: fix RPROVIDES_PN = PN-systemd in entrance
MJ: add RPROVIDES for ntp*-systemd in ntp
MJ: the same for wpa-supplicant

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>