systemd.bbclass: update command to check systemctl available
When use a core image with systemd as docker image, it fails to
install/remove package which calls systemctl in post scripts.
It fails to run systemctl in a container:
bash-5.0# systemctl
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
So replace the criterion command 'type systemctl' with 'systemctl' in
package post scripts to check whether systemctl available.
Signed-off-by: Kai Kang <kai.kang@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
