ARM platforms: Make arm_validate_ns_entrypoint() common

The function arm_validate_ns_entrypoint() validates a given non-secure
physical address. This function however specifically returns PSCI error
codes.

Non-secure physical address validation is potentially useful across ARM
platforms, even for non-PSCI use cases. Therefore make this function
common by returning 0 for success or -1 otherwise.

Having made the function common, make arm_validate_psci_entrypoint() a
wrapper around arm_validate_ns_entrypoint() which only translates return
value into PSCI error codes. This wrapper is now used where
arm_validate_ns_entrypoint() was currently used for PSCI entry point
validation.

Change-Id: Ic781fc3105d6d199fd8f53f01aba5baea0ebc310
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/plat/arm/board/fvp/fvp_pm.c b/plat/arm/board/fvp/fvp_pm.c
index faeb1b7..0ab5b82 100644
--- a/plat/arm/board/fvp/fvp_pm.c
+++ b/plat/arm/board/fvp/fvp_pm.c
@@ -398,7 +398,7 @@
 	.system_off = fvp_system_off,
 	.system_reset = fvp_system_reset,
 	.validate_power_state = fvp_validate_power_state,
-	.validate_ns_entrypoint = arm_validate_ns_entrypoint,
+	.validate_ns_entrypoint = arm_validate_psci_entrypoint,
 	.translate_power_state_by_mpidr = fvp_translate_power_state_by_mpidr,
 	.get_node_hw_state = fvp_node_hw_state,
 	.get_sys_suspend_power_state = fvp_get_sys_suspend_power_state,