dm: adc: add iMX93 ADC support

This commit adds driver for iMX93 ADC.

The driver is implemented using driver model and provides
ADC uclass's methods for ADC single channel operations:
    - adc_start_channel()
    - adc_channel_data()
    - adc_stop()

ADC features:
    - channels: 4
    - resolution: 12-bit

Signed-off-by: Luca Ellero <l.ellero@asem.it>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>