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.

(From OE-Core rev: a52e66762c0c51918b1ba3d4622759637b6e920a)

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/systemd.bbclass

@@ -23,7 +23,7 @@ python __anonymous() {
 }
 
 systemd_postinst() {
-if type systemctl >/dev/null 2>/dev/null; then
+if systemctl >/dev/null 2>/dev/null; then
 	OPTS=""
 
 	if [ -n "$D" ]; then
@@ -48,7 +48,7 @@ fi
 }
 
 systemd_prerm() {
-if type systemctl >/dev/null 2>/dev/null; then
+if systemctl >/dev/null 2>/dev/null; then
 	if [ -z "$D" ]; then
 		systemctl stop ${SYSTEMD_SERVICE_ESCAPED}