mdadm: install the systemd service through Makefile
The original mdadm service may include variable like BINDIR,
It should use the real value of it, since the install method
"install-systemd" in Makefile can easily do such work, so don't
install it in bb file manually, use "make install-systemd" to
install all the service of mdadm.
Signed-off-by: Liwei Song <liwei.song@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
