scripts/kernel-doc.py: Set an output format for --none

Now that warnings output is deferred to the output plugin, we
need to have an output style for none as well.

So, use the OutputFormat base class on such cases.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/caa1089e16f4609f792ff26731ad9e9c3a6f6b1d.1744106242.git.mchehab+huawei@kernel.org

scripts/lib/kdoc/kdoc_files.py

@@ -20,6 +20,7 @@ from datetime import datetime
 from dateutil import tz
 
 from kdoc_parser import KernelDoc
+from kdoc_output import OutputFormat
 
 
 class GlobSourceFiles:
@@ -138,6 +139,9 @@ class KernelFiles():
         if not modulename:
             modulename = "Kernel API"
 
+        if out_style is None:
+            out_style = OutputFormat()
+
         dt = datetime.now()
         if os.environ.get("KBUILD_BUILD_TIMESTAMP", None):
             # use UTC TZ