stm32: Move clock line mapping from stm32h7_adc.c to lookup_clock_line()

Use the common lookup_clock_line() code to lookup the adc clock lines.
This also enables resets on the adc1/adc2 hardware block.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/stm32/stm32l4.c

@@ -42,7 +42,7 @@ lookup_clock_line(uint32_t periph_base)
                               .rst = &RCC->AHB1RSTR,
                               .bit = 1 << pos};
 
-    } else if (periph_base == ADC1_BASE) {
+    } else if (periph_base == ADC12_COMMON_BASE) {
         return (struct cline){.en = &RCC->AHB2ENR,
                               .rst = &RCC->AHB2RSTR,
                               .bit = RCC_AHB2ENR_ADCEN};