MAINTAINERS: USB: add uapi header files to USB SUBSYSTEM entry

For some reason the include/uapi/linux/usb/ directory is missing in the
USB SUBSYSTEM entry, so get_maintainer will not know to cc: the proper
mailing lists.  Fix this up by adding an entry for this directory.

Message-ID: <20230615094306.2072827-2-gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -21941,6 +21941,7 @@ F:	drivers/usb/
 F:	include/dt-bindings/usb/
 F:	include/linux/usb.h
 F:	include/linux/usb/
+F:	include/uapi/linux/usb/
 
 USB TYPEC BUS FOR ALTERNATE MODES
 M:	Heikki Krogerus <heikki.krogerus@linux.intel.com>