i2c: rtl9300: add RTL9607C i2c controller support

i2c: rtl9300: add RTL9607C i2c controller support

Add support for the internal I2C controllers of RTL9607C series based
SoCs. Add register definitions, chip-specific functions and macros too.

Make use of the clk introduced from the previous patch to get the clk_div
value and use it during the rtl9607c channel configuration.

Introduce a new EXT_SCK_5MS field to the reg fields struct which is going
to be initialized by rtl9607c init function at the end of the probe.

This patch depends on all the previous patches in this patch series.

Signed-off-by: Rustam Adilov <adilov@disroot.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260401180648.337834-9-adilov@disroot.org