ensure stop-instructions service stopped during istep

IBM systems utilize istep to boot a system in a more manual "debug
mode". istep does not utilize the host systemd targets to boot the
system, and instead directly communicates with the host firmware to boot
the system.

This results in the obmc-host-* targets not being run as a part of the
boot, which results in op-stop-instructions@.service.in not getting it's
"Conflicts" operation to run. This means after an istep boot, the
op-stop-instruction@.service has not properly stopped, which results in
it not properly running during the power off of the next boot.

Because op-stop-instruction@.service is now responsible for stopping the
attn handler, this is not a good situation.

istep boots however do still utilize the obmc-chassis-poweron@.target to
power the system on. Add a Conflits for this target to ensure
op-stop-instructions@.service is stopped in all scenarios. Leave the
Conflits with obmc-host-startmin@.target to ensure the service is still
properly stopped on warm reboots.

Tested:
- Performed an istep boot, and verified during the subsequent power off
  that op-stop-instructions@0.service was properly run

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I647fae0638468a0c35842d91be8ced2acda59a6b
diff --git a/service_files/op-stop-instructions@.service.in b/service_files/op-stop-instructions@.service.in
index 06b9f67..b252e1e 100644
--- a/service_files/op-stop-instructions@.service.in
+++ b/service_files/op-stop-instructions@.service.in
@@ -5,6 +5,7 @@
 After=op-occ-disable@%i.service
 After=openpower-update-bios-attr-table.service
 Conflicts=obmc-host-startmin@%i.target
+Conflicts=obmc-chassis-poweron@%i.target
 ConditionPathExists=/sys/class/fsi-master/fsi0/slave@00:00/cfam_id
 ConditionPathExists=!/run/openbmc/mpreboot@%i