refactor(ti): add top level ti_sci transport layer

The TI SCI transport header will allow us to abstract all transport
related calls from the actual medium of transport which can vary
from device to device.
For eg. it is sec proxy for current TI K3 devices, but in future it
maybe mailbox like in the TI AM62L.
With this change, we no longer need to include anything from the IPC
folder, so drop it from plat_common.mk

Change-Id: Ic99209688cf69f20e694e31e553ce4ec74254669
Signed-off-by: Dhruva Gole <d-gole@ti.com>
diff --git a/drivers/ti/ipc/sec_proxy.c b/drivers/ti/ipc/sec_proxy.c
index fb27336..30c7ced 100644
--- a/drivers/ti/ipc/sec_proxy.c
+++ b/drivers/ti/ipc/sec_proxy.c
@@ -2,7 +2,7 @@
  * Texas Instruments K3 Secure Proxy Driver
  *   Based on Linux and U-Boot implementation
  *
- * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Copyright (C) 2018-2025 Texas Instruments Incorporated - http://www.ti.com/
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -18,7 +18,7 @@
 #include <lib/utils.h>
 #include <lib/utils_def.h>
 
-#include "sec_proxy.h"
+#include <ti_sci_transport.h>
 
 /* SEC PROXY RT THREAD STATUS */
 #define RT_THREAD_STATUS			(0x0)