ARM: dts: sun6i: Change clock node names to avoid warnings

Our oscillators clock names have a unit address, but no reg property, which
generates a warning in DTC. Change these names to remove those unit
addresses.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>