SPM: Change data type of irq line to uint32_t

This patch changes the data type of irq line from IRQn_Type to
uint32_t to remove the platform dependency.
Also updated the get_irq_line_for_signal function to align between
the two models.

Change-Id: Ifc381b913d60797b06facd8ccb5d26ba01327372
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/secure_fw/spm/cmsis_psa/spm_ipc.h b/secure_fw/spm/cmsis_psa/spm_ipc.h
index 1af5945..3328a30 100644
--- a/secure_fw/spm/cmsis_psa/spm_ipc.h
+++ b/secure_fw/spm/cmsis_psa/spm_ipc.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2020-2021, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -507,15 +507,11 @@
  * \param[in]      partition_id    The ID of the partition in which we look for
  *                                 the signal.
  * \param[in]      signal          The signal we do the query for.
- * \param[out]     irq_line        The irq line associated with signal
  *
- * \retval IPC_SUCCESS          Execution successful, irq_line contains a valid
- *                              value.
- * \retval IPC_ERROR_GENERIC    There was an error finding the IRQ line for the
+ * \retval None-negative value  The irq line associated with signal
+ * \retval Negative value       There was an error finding the IRQ line for the
  *                              signal. irq_line is unchanged.
  */
-int32_t get_irq_line_for_signal(int32_t partition_id,
-                                psa_signal_t signal,
-                                IRQn_Type *irq_line);
+int32_t get_irq_line_for_signal(int32_t partition_id, psa_signal_t signal);
 
 #endif /* __SPM_IPC_H__ */