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/plat/imx/imx8m/imx8mq/imx8mq_psci.c b/plat/imx/imx8m/imx8mq/imx8mq_psci.c
index 3375ce7..c023b55 100644
--- a/plat/imx/imx8m/imx8mq/imx8mq_psci.c
+++ b/plat/imx/imx8m/imx8mq/imx8mq_psci.c
@@ -137,7 +137,7 @@
 	.cpu_standby = imx_cpu_standby,
 	.pwr_domain_suspend = imx_domain_suspend,
 	.pwr_domain_suspend_finish = imx_domain_suspend_finish,
-	.pwr_domain_pwr_down_wfi = imx_pwr_domain_pwr_down_wfi,
+	.pwr_domain_pwr_down = imx_pwr_domain_pwr_down_wfi,
 	.get_sys_suspend_power_state = imx_get_sys_suspend_power_state,
 	.system_reset = imx_system_reset,
 	.system_reset2 = imx_system_reset2,