arm64: dts: stratix10: i2c clock running out of spec

DesignWare I2C controller was observed running at 105.93kHz rather
than the specified 100kHz.  Adjust device tree settings to bring it
within spec (a slightly conservative 98 MHz).

Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>