App: Clarify the initial_count parameter in semaphore creation API

Clarify that the initial_count in os_wrapper_semaphore_create()
indicates the initial number of available tokens.

Change-Id: Ia16b77b5f982a6a911bf4509faf215d4402f4a48
Signed-off-by: David Hu <david.hu@arm.com>
diff --git a/interface/include/os_wrapper/semaphore.h b/interface/include/os_wrapper/semaphore.h
index 89b00a0..83d88ca 100644
--- a/interface/include/os_wrapper/semaphore.h
+++ b/interface/include/os_wrapper/semaphore.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019, Arm Limited. All rights reserved.
+ * Copyright (c) 2017-2020, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -18,7 +18,7 @@
  * \brief Creates a new semaphore
  *
  * \param[in] max_count       Highest count of the semaphore
- * \param[in] initial_count   Starting count of the semaphore
+ * \param[in] initial_count   Starting count of the available semaphore
  * \param[in] name            Name of the semaphore
  *
  * \return Returns handle of the semaphore created, or NULL in case of error