clang-format: Remove unsupported option

The CaseSensitive option requires clang-format 12 which is not widely
available.

Remove the option, to fix clang-format uses until a solution which
supports clang-format version specific configurations can be merged.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

.clang-format

@@ -77,7 +77,6 @@ IncludeCategories:
   # Qt includes (match before C++ standard library)
   - Regex:           '<Q([A-Za-z0-9\-_])+>'
     Priority:        9
-    CaseSensitive:   true
   # Headers in <> with an extension. (+system libraries)
   - Regex:           '<([A-Za-z0-9\-_])+\.h>'
     Priority:        2