configs: Fix waiting on remote debugger

Commit 2c75e58cac ("sim,cpu: Move the remote GDB stub
into the workload.") moved "wait_for_remote_gdb" to the
Workload class. That breaks se.py since it continues to
rely on that being a property of BaseCPU. This ensures
that the property is now set via the current Workload
instance instead.

Also, owing to its boolean nature, the argument should
ideally not expect any additional values. Hence, it is
associated with the "store_true" action.

Change-Id: I4a00b29d283df36ebf833c9125651cd6deb52a4f
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47360
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Maintainer: Boris Shingarov <shingarov@labware.com>
Tested-by: kokoro <noreply+kokoro@google.com>

configs/common/Options.py

@@ -455,7 +455,7 @@ def addSEOptions(parser):
                         "to be used in syscall emulation."
                         "Usage: gem5.opt [...] --redirects /dir1=/path/"
                         "to/host/dir1 --redirects /dir2=/path/to/host/dir2")
-    parser.add_argument("--wait-gdb", default=False,
+    parser.add_argument("--wait-gdb", default=False, action='store_true',
                         help="Wait for remote GDB to connect.")