Remove unused argument in psci_cpu_on_start()

The "end power level" value passed as the 3rd argument to the
psci_cpu_on_start() function is not used so this patch removes it.

Change-Id: Icaa68b8c4ecd94507287970455fbff354faaa41e
diff --git a/services/std_svc/psci/psci_main.c b/services/std_svc/psci/psci_main.c
index e6cd3a3..68ad5f6 100644
--- a/services/std_svc/psci/psci_main.c
+++ b/services/std_svc/psci/psci_main.c
@@ -47,7 +47,6 @@
 
 {
 	int rc;
-	unsigned int end_pwrlvl;
 	entry_point_info_t ep;
 
 	/* Determine if the cpu exists of not */
@@ -64,11 +63,7 @@
 	 * To turn this cpu on, specify which power
 	 * levels need to be turned on
 	 */
-	end_pwrlvl = PLAT_MAX_PWR_LVL;
-	rc = psci_cpu_on_start(target_cpu,
-			    &ep,
-			    end_pwrlvl);
-	return rc;
+	return psci_cpu_on_start(target_cpu, &ep);
 }
 
 unsigned int psci_version(void)