arm/classes: Change FVP_CONSOLE to FVP_CONSOLES in fvpconf

So that the test target can connect to the desired console(s) as soon
as they appear in the FVP stdout, add the variable FVP_CONSOLES to the
fvpconf as a replcaement for FVP_CONSOLE. The varflags of this variable
define a mapping between FVP console names (e.g. terminal_0) and console
names in the tests (e.g. 'zephyr'). The console defined in
FVP_CONSOLE is automatically mapped as 'default' for backwards
compatibility.

This also enables greater reuse of test cases, as the "default" console
name can be remapped on a per-machine basis.

Issue-Id: SCM-4957
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Change-Id: I9d88b172bfc5a5459b9f5132f287c70816d7fb55
Signed-off-by: Jon Mason <jon.mason@arm.com>

scripts/runfvp

@@ -55,7 +55,7 @@ async def start_fvp(args, config, extra_args):
 
         if args.console:
             fvp.add_line_callback(lambda line: logger.debug(f"FVP output: {line}"))
-            expected_terminal = config["console"]
+            expected_terminal = config["consoles"]["default"]
             if not expected_terminal:
                 logger.error("--console used but FVP_CONSOLE not set in machine configuration")
                 return 1