arm64: dts: exynos: Remove undocumented i2s properties in Exynos5433

Few I2S device node properties were not documented and not used by any
of the drivers.  Remove them to fix dtbs_check warning:

  arch/arm64/boot/dts/exynos/exynos5433-tm2.dt.yaml: i2s@14d60000:
    Additional properties are not allowed ('samsung,supports-rstclr', 'samsung,supports-tdm',
    'samsung,supports-6ch', 'samsung,supports-low-rfs' were unexpected)

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200903203250.19830-3-krzk@kernel.org