dracut: Support /usr/bin as 'systemctl' path

On openSUSE the initrd has systemctl in /usr/bin, check this path as
well.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Lorenz Hüdepohl <dev@stellardeath.org>
Closes openzfs#11487

contrib/dracut/90zfs/zfs-env-bootfs.service.in

@@ -8,7 +8,7 @@ Before=zfs-import.target
 
 [Service]
 Type=oneshot
-ExecStart=/bin/sh -c "/bin/systemctl set-environment BOOTFS=$(@sbindir@/zpool list -H -o bootfs | grep -m1 -v '^-$')"
+ExecStart=/bin/sh -c "systemctl set-environment BOOTFS=$(@sbindir@/zpool list -H -o bootfs | grep -m1 -v '^-$')"
 
 [Install]
 WantedBy=zfs-import.target

contrib/dracut/90zfs/zfs-load-key.sh.in

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 # only run this on systemd systems, we handle the decrypt in mount-zfs.sh in the mount hook otherwise
-[ -e /bin/systemctl ] || return 0
+[ -e /bin/systemctl ] || [ -e /usr/bin/systemctl ] || return 0
 
 # This script only gets executed on systemd systems, see mount-zfs.sh for non-systemd systems