scripts: utils: add sys_init migration script

Utility script to migrate SYS_INIT() calls from the old signature:

```c
int (*init_fn)(const struct device *dev)
```
to

```c
int (*init_fn)(void)
```

Signed-off-by: Gerard Marull-Paretas <[email protected]>

Author: gmarull

scripts/utils/migrate_sys_init.py

@@ -0,0 +1,86 @@
+"""
+Utility script to migrate SYS_INIT() calls from the old signature
+``int (*init_fn)(const struct device *dev)`` to ``int (*init_fn)(void)``.
+
+.. warning::
+    Review the output carefully! This script may not cover all cases!
+
+Usage::
+
+    python $ZEPHYR_BASE/scripts/utils/migrate_sys_init.py \
+           -p path/to/zephyr-based-project
+
+Copyright (c) 2022 Nordic Semiconductor ASA
+SPDX-License-Identifier: Apache-2.0
+"""
+
+import argparse
+from pathlib import Path
+import re
+
+
+ZEPHYR_BASE = Path(__file__).parents[2]
+
+
+def update_sys_init(project, dry_run):
+    for p in project.glob("**/*"):
+        if not p.is_file() or not p.suffix or p.suffix[1:] not in ("c", "cpp"):
+            continue
+
+        with open(p) as f:
+            lines = f.readlines()
+
+        sys_inits = []
+        for line in lines:
+            m = re.match(r"^SYS_INIT\(([A-Za-z0-9_]+),.*", line)
+            if m:
+                sys_inits.append(m.group(1))
+                continue
+
+            m = re.match(r"^SYS_INIT_NAMED\([A-Za-z0-9_]+,\s?([A-Za-z0-9_]+).*", line)
+            if m:
+                sys_inits.append(m.group(1))
+                continue
+
+        if not sys_inits:
+            continue
+
+        arg = None
+        content = ""
+        update = False
+        for line in lines:
+            m = re.match(
+                r"(.*)int ("
+                + "|".join(sys_inits)
+                + r")\(const\s+struct\s+device\s+\*\s?(.*)\)(.*)",
+                line,
+            )
+            if m:
+                b, sys_init, arg, e = m.groups()
+                content += f"{b}int {sys_init}(void){e}\n"
+                update = True
+            elif arg:
+                m = re.match(r"^\s?ARG_UNUSED\(" + arg + r"\);.*$", line)
+                if m:
+                    arg = None
+                else:
+                    content += line
+            else:
+                content += line
+
+        if update:
+            print(f"Updating {p}{' (dry run)' if dry_run else ''}")
+            if not dry_run:
+                with open(p, "w") as f:
+                    f.write(content)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(allow_abbrev=False)
+    parser.add_argument(
+        "-p", "--project", type=Path, required=True, help="Zephyr-based project path"
+    )
+    parser.add_argument("--dry-run", action="store_true", help="Dry run")
+    args = parser.parse_args()
+
+    update_sys_init(args.project, args.dry_run)