configs/nucleo-f207zg, configs/nucleo-f103rb: add ADC and PWM examples; arch/arm/src/stm32_adc.c: there is no DMA CFG bit for the basic IPv1 ADC Approved-by: GregoryN <gnutt@nuttx.org>
configs: add support for nucleo-f103rb, nucleo-f207zg and nucleo-l152re Approved-by: GregoryN <gnutt@nuttx.org>