clk: ti: add divider clock driver

The patch adds support for TI divider clock binding. The driver uses
routines provided by the common clock framework (ccf).

The code is based on the drivers/clk/ti/divider.c driver of the Linux
kernel version 5.9-rc7.
For DT binding details see:
- Documentation/devicetree/bindings/clock/ti/divider.txt

Signed-off-by: Dario Binacchi <dariobin@libero.it>