Amend the DT bindings to include the optional clock sources for the Baud
Rate Generator for External Clock (BRG), as found on some SCIF variants
and on HSCIF.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>