Make setjmp.h prototypes comply with the C standard

Instead of having a custom implementation of setjmp() and longjmp() it
is better to follow the C standard.

The comments in setjmp.h are no longer needed as there are no deviations
from the expected one, so they have been removed.

All SDEI code that relied on them has been fixed to use the new function
prototypes and structs.

Change-Id: I6cd2e21cb5a5bcf81ba12283f2e4c067bd5172ca
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/services/std_svc/sdei/sdei_dispatch.S b/services/std_svc/sdei/sdei_dispatch.S
index a7a4a40..8449e4b 100644
--- a/services/std_svc/sdei/sdei_dispatch.S
+++ b/services/std_svc/sdei/sdei_dispatch.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,7 +9,7 @@
 	.globl	begin_sdei_synchronous_dispatch
 
 /*
- * void begin_sdei_synchronous_dispatch(struct jmpbuf *buffer);
+ * void begin_sdei_synchronous_dispatch(jmp_buf *buffer);
  *
  * Begin SDEI dispatch synchronously by setting up a jump point, and exiting
  * EL3. This jump point is jumped to by the dispatcher after the event is