plat/arm: remove weak implemention of 'plat_arm_psci_override_pm_ops' function

In order to allow Arm platforms to override the default list of PSCI
callbacks, remove the existing weak implementation of
'plat_arm_psci_override_pm_ops' function and let all the Arm platforms
implement their own 'plat_arm_psci_override_pm_ops' function.

For platforms that support SCMI protocol, the function
'css_scmi_override_pm_ops' can be additionally used as well to
override the default PSCI callbacks.

Change-Id: If7c27468bd51a00ea9c2a3716b5894163f5a9f3c
Signed-off-by: Chandni Cherukuri <chandni.cherukuri@arm.com>
diff --git a/plat/arm/board/n1sdp/n1sdp_bl31_setup.c b/plat/arm/board/n1sdp/n1sdp_bl31_setup.c
index 65aad9c..cdd0b63 100644
--- a/plat/arm/board/n1sdp/n1sdp_bl31_setup.c
+++ b/plat/arm/board/n1sdp/n1sdp_bl31_setup.c
@@ -6,6 +6,7 @@
 
 #include "../../css/drivers/scmi/scmi.h"
 #include "../../css/drivers/mhu/css_mhu_doorbell.h"
+#include <plat_arm.h>
 #include <platform_def.h>
 
 static scmi_channel_plat_info_t n1sdp_scmi_plat_info = {
@@ -20,3 +21,8 @@
 {
 	return &n1sdp_scmi_plat_info;
 }
+
+const plat_psci_ops_t *plat_arm_psci_override_pm_ops(plat_psci_ops_t *ops)
+{
+	return css_scmi_override_pm_ops(ops);
+}