Refactors all of the clock control drivers to use a shared driver class
initialization priority configuration,
CONFIG_CLOCK_CONTROL_INIT_PRIORITY, to allow configuring clock control
drivers separately from other devices. This is similar to other driver
classes like I2C and SPI.
Most drivers previously used CONFIG_KERNEL_INIT_PRIORITY_OBJECTS or
CONFIG_KERNEL_INIT_PRIORITY_DEVICE, therefore the default for this new
option is the lower of the two, which means earlier initialization.
The even lower defaults for STM32 and Arm Beetle are preserved by
SoC-family level overrides.
Signed-off-by: Maureen Helm <maureen.helm@intel.com>
