clock_control: Introduce mcux sim driver

Adds a new clock control driver for Kinetis SoCs that have the system
integration (SIM) module. This will allow mcux shim drivers, such as
uart and i2c, to abstract the call to CLOCK_GetFreq() behind the
clock_control interface and thus be reused for SoCs with different clock
architectures.

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>