meta-facebook: harma: fix bios update poweroff command

The power-off command in the BIOS update script has been fixed
because we modified the power-cmd script in:

71673: meta-facebook: harma: revise PSM behavior
https://gerrit.openbmc.org/c/openbmc/openbmc/+/71673

However, it was not modified here.

Change-Id: I4c35134054dc4966d2cb08be81c52a141c0aff9f
Signed-off-by: Peter Yin <peter.yin@quantatw.com>
diff --git a/meta-facebook/meta-harma/recipes-phosphor/flash/phosphor-software-manager/bios-update.sh b/meta-facebook/meta-harma/recipes-phosphor/flash/phosphor-software-manager/bios-update.sh
index b21c5d2..25bde6d 100755
--- a/meta-facebook/meta-harma/recipes-phosphor/flash/phosphor-software-manager/bios-update.sh
+++ b/meta-facebook/meta-harma/recipes-phosphor/flash/phosphor-software-manager/bios-update.sh
@@ -31,7 +31,8 @@
 
 #Power off host server.
 echo "Power off host server"
-power_off
+obmcutil poweroff
+
 sleep 15
 if [ "$(power_status)" != "off" ];
 then