ARM: renesas: Drop old unused clock DT headers

ARM: renesas: Drop old unused clock DT headers

Renesas R-Car systems use mainline Linux DTs for U-Boot via OF_UPSTREAM,
which also includes headers from dts/upstream/include/dt-bindings/clock .
Remove unused legacy DT header files from include/dt-bindings/clock .

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>