fix(sc7280): update system suspend in OS-initiated mode

This patch fixes system suspend in OS-initiated mode by setting the
value of `last_at_pwrlvl` in the `psci_power_state_t` object to
`PLAT_MAX_PWR_LVL`, which otherwise would result in undefined behavior.

This is conditionally compiled into the build depending on the value of
the `PSCI_OS_INIT_MODE` build option.

Change-Id: Ib9ff606b7eebd8a8224891a0d239a4e13311fe2a
Signed-off-by: Wing Li <wingers@google.com>

plat/qti/common/src/qti_pm.c

@@ -260,6 +260,10 @@ void qti_get_sys_suspend_power_state(psci_power_state_t *req_state)
 		    state_id & QTI_LOCAL_PSTATE_MASK;
 		state_id >>= QTI_LOCAL_PSTATE_WIDTH;
 	}
+
+#if PSCI_OS_INIT_MODE
+	req_state->last_at_pwrlvl = PLAT_MAX_PWR_LVL;
+#endif
 }
 
 /*