freedreno: make gen_header.py check parent directory

With the next commit, the xml files will be no longer be all in the same
directory.  But checking up a single directory level to resolve import
will be sufficient.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6070>

src/freedreno/registers/gen_header.py

@@ -332,7 +332,14 @@ class Parser(object):
 			raise self.error(e);
 
 	def do_parse(self, filename):
-		file = open(filename, "rb")
+		try:
+			file = open(filename, "rb")
+		except FileNotFoundError as e:
+			# Look for the file in the parent directory if not
+			# found in same directory:
+			path = os.path.dirname(filename)
+			base = os.path.basename(filename)
+			file = open(path + "/../" + base, "rb")
 		parser = xml.parsers.expat.ParserCreate()
 		self.stack.append((parser, filename))
 		parser.StartElementHandler = self.start_element