test: driver: adc: add some nucleo boards support for adc test cases

Some configuration for the boards have to be added into test_adc.c file
so user can test driver with the test cases. Several nucleo boards are
added including F091RC/F103RB/F207ZG/F302R8/F401RE/F746ZG/L073RZ/L476RG.

And also ADC dts and pinmux configuration are added into boards own
pinmux.c and dts file.

Signed-off-by: Song Qiang <songqiang1304521@gmail.com>