charger:driver:fix non power off issue for factory kill.

In P, run_cmd(poweroff_cmd) can work to trigger /sbin/poweroff. Now in
R, it can not work but still return success. We need to use
kernel_power_off() to trigger power off for factory kill.
The change is referring to (CR).

Change-Id: Ia18faee3138259c7ee35946313e9b0dac75dd244
Signed-off-by: xieqiong2 <xieqiong2@lenovo.com>
Reviewed-on: https://gerrit.mot.com/1763914
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key

drivers/power/supply/qcom/smb5-lib.c

@@ -6115,7 +6115,7 @@ void smblib_usb_plugin_locked(struct smb_charger *chg)
 
 		if (chg->mmi.factory_kill_armed && !factory_kill_disable) {
 			smblib_err(chg, "Factory kill power off\n");
-			orderly_poweroff(true);
+                        kernel_power_off();
 		} else
 			chg->mmi.factory_kill_armed = false;
 	}