chore(docs): drop the "wfi" from `pwr_domain_pwr_down_wfi`

To allow for generic handling of a wakeup, this hook is no longer
expected to call wfi itself. Update the name everywhere to reflect this
expectation so that future platform implementers don't get misled.

Change-Id: Ic33f0b6da74592ad6778fd802c2f0b85223af614
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/include/lib/psci/psci.h b/include/lib/psci/psci.h
index 3a5bdba..68e721a 100644
--- a/include/lib/psci/psci.h
+++ b/include/lib/psci/psci.h
@@ -331,7 +331,7 @@
 				const psci_power_state_t *target_state);
 	void (*pwr_domain_suspend_finish)(
 				const psci_power_state_t *target_state);
-	void (*pwr_domain_pwr_down_wfi)(
+	void (*pwr_domain_pwr_down)(
 				const psci_power_state_t *target_state);
 	void (*system_off)(void);
 	void (*system_reset)(void);