ARM: zynq: dts: Setting default i2c clock frequency to 400kHz

Setting default i2c clock frequency for Zynq to maximum rate of 400kHz.
Current default value is 100kHz.

Signed-off-by: Varalaxmi Bingi <varalaxmi.bingi@amd.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/4dde5d1eb8e4572dae4295a19a4c83002a58e5da.1683035611.git.michal.simek@amd.com