i2c: thunderx: Clock divisor logic changes

Handle changes to clock divisor logic for OcteonTX2 SoC family using
subsystem ID and using default reference clock source as 100MHz.

Signed-off-by: Suneel Garapati <sgarapati@marvell.com>
Signed-off-by: Piyush Malgujar <pmalgujar@marvell.com>
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>