ASoC: max98363: limit the number of channel to 1

MAX98363 is a mono amplifier. The number of channel needs to be always 1.

Signed-off-by: Ryan Lee <ryans.lee@analog.com>
Link: https://lore.kernel.org/r/20230601130600.25344-2-ryan.lee.analog@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>