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/css/drivers/scmi/scmi.h b/plat/arm/css/drivers/scmi/scmi.h
index e1358bf..28dfc9a 100644
--- a/plat/arm/css/drivers/scmi/scmi.h
+++ b/plat/arm/css/drivers/scmi/scmi.h
@@ -8,6 +8,7 @@
 #define SCMI_H
 
 #include <bakery_lock.h>
+#include <psci.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <spinlock.h>
@@ -162,4 +163,7 @@
 /* API to get the platform specific SCMI channel information. */
 scmi_channel_plat_info_t *plat_css_get_scmi_info();
 
+/* API to override default PSCI callbacks for platforms that support SCMI. */
+const plat_psci_ops_t *css_scmi_override_pm_ops(plat_psci_ops_t *ops);
+
 #endif /* SCMI_H */