ASoC: dt-bindings: fsl-sai: Use minItems 5 for i.MX8MN clock and similar

The i.MX8MN currently uses "bus", "mclk0", "mclk1", "mclk2", "mclk3"
clock, which adds up to 5 clock total. Use minItems 5 for this setup.

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221104160315.213836-2-marex@denx.de


Signed-off-by: Mark Brown <broonie@kernel.org>