stm32/machine_adc: Handle ADC resolution less than 8 bits on all MCUs.

All MCUs can have 6-bit resolution; see adc_cr_to_bits_table. Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

ports/stm32/machine_adc.c

@@ -374,12 +374,10 @@ uint32_t adc_config_and_read_u16(ADC_TypeDef *adc, uint32_t channel, uint32_t sa
 
  // Scale raw reading to 16 bit value using a Taylor expansion (for bits <= 16).
  uint32_t bits = adc_get_bits(adc);
- #if defined(STM32H7)
  if (bits < 8) {
  // For 6 and 7 bits
  return raw << (16 - bits) | raw << (16 - 2 * bits) | raw >> (3 * bits - 16);
  }
- #endif
  return raw << (16 - bits) | raw >> (2 * bits - 16);
 }