ASoC: sun4i-i2s: fix coding-style for callback definition

Checkpatch script produces warning:
WARNING: function definition argument 'const struct sun4i_i2s *'
should also have an identifier name.

Let's fix this by adding identifier name to get_bclk_parent_rate()
and set_fmt() callback definition.

Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Link: https://lore.kernel.org/r/20201030144648.397824-10-peron.clem@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>