arm64: dts: allwinner: a64: Fix the Codec I2S binding

The I2S binding never mentions a reset-names property, or mentions which
value it should have. To avoid any further issue, remove it.

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