drivers: clock_control: Configure STM clock

1.Add "mux-1-dc-0-div" and "mux-2-dc-0-div" property
 in mc_cgm device tree for STM clock divider setting
 and set these properties in frdm_mcxe31b.dts
2.Enable STM peripheral clock in mc_cgm_clock_control_on
 function
3.Support to get STM frequency from mc_cgm_get_subsys_rate
 function
4.Configure STM clock in mc_cgm_init function

Signed-off-by: Felix Wang <fei.wang_3@nxp.com>
4 files changed