xtensa-build-zephyr.py: switch default to sof/stable-v2.2

The release branch is created for SOF v2.2 in the cloned Zephyr repo:
https://github.com/thesofproject/zephyr/tree/sof/stable-v2.2

This points to unmodified Zephyr upstream tag v3.1.0-rc3

Set default Zephyr URL to this cloned repo and switch default branch
to sof/stable-v2.2

Signed-off-by: mengdonglin <mengdong.lin@intel.com>

Author: mengdonglin

scripts/xtensa-build-zephyr.py

@@ -144,7 +144,7 @@ def parse_args():
 						help="Initial Zephyr git ref for the -c option."
 						" Can be a branch, tag, full SHA1 in a fork")
 	parser.add_argument("-u", "--url", required=False,
-						default="https://github.com/zephyrproject-rtos/zephyr/",
+						default="https://github.com/thesofproject/zephyr/",
 						help="URL to clone Zephyr from")
 	mode_group = parser.add_mutually_exclusive_group()
 	mode_group.add_argument("-p", "--west_path", required=False, type=pathlib.Path,
@@ -197,7 +197,7 @@ def parse_args():
 	if args.zephyr_ref and not args.clone_mode:
 		raise RuntimeError(f"Argument -z without -c makes no sense")
 	if args.clone_mode and not args.zephyr_ref:
-		args.zephyr_ref = "main"	# set default name for -z if -c specified
+		args.zephyr_ref = "sof/stable-v2.2"	# set default name for -z if -c specified
 
 	if args.west_path: # let the user provide an already existing zephyrproject/ anywhere
 		west_top = pathlib.Path(args.west_path)