arm64: dts: ls1028a: Fix incorrect I2C clock divider

Ls1028a platform, the i2c input clock is actually platform pll CLK / 4
(this is the hardware connection), other clock divider can not get the
correct i2c clock, resulting in the output of SCL pin clock is not
accurate.

Signed-off-by: Chuanhua Han <chuanhua.han@nxp.com>
Acked-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>