drivers: i2c: npcx: add more timing parameters for I2C clock frequency

I2C Fast-Plus mode (1 MHz) is limited by the source clock.
For example, with a 15 MHz I2C source clock, the max I2C frequency is
~625 kHz. To support higher I2C frequencies, the APBx source clock must
be increased. This commit adds the timing parameters for I2C operation
at higher APBx clocks.

Signed-off-by: Jun Lin <CHLin56@nuvoton.com>