MAINTAINERS: Cover qapi/cxl.json

Commit 415442a (hw/mem/cxl_type3: Add CXL RAS Error Injection
Support.) created qapi/cxl.json without adding it to MAINTAINERS.  Fix
that.

Cc: Ben Widawsky <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Fan Ni <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Signed-off-by: Michael Tokarev <[email protected]>

Author: Markus Armbruster

MAINTAINERS

@@ -2894,6 +2894,7 @@ S: Supported
 F: hw/cxl/
 F: hw/mem/cxl_type3.c
 F: include/hw/cxl/
+F: qapi/cxl.json
 
 Dirty Bitmaps
 M: Eric Blake <[email protected]>