Don't return error information from console_flush

And from crash_console_flush.

We ignore the error information return by console_flush in _every_
place where we call it, and casting the return type to void does not
work around the MISRA violation that this causes. Instead, we collect
the error information from the driver (to avoid changing that API), and
don't return it to the caller.

Change-Id: I1e35afe01764d5c8f0efd04f8949d333ffb688c1
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
diff --git a/include/drivers/console.h b/include/drivers/console.h
index 761816a..99bf960 100644
--- a/include/drivers/console.h
+++ b/include/drivers/console.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -43,7 +43,7 @@
 	u_register_t flags;
 	int (*const putc)(int character, struct console *console);
 	int (*const getc)(struct console *console);
-	int (*const flush)(struct console *console);
+	void (*const flush)(struct console *console);
 	uintptr_t base;
 	/* Additional private driver data may follow here. */
 } console_t;
@@ -76,7 +76,7 @@
 /* Read a character (blocking) from any console registered for current state. */
 int console_getc(void);
 /* Flush all consoles registered for the current state. */
-int console_flush(void);
+void console_flush(void);
 
 #endif /* __ASSEMBLER__ */