Implement Calibrate stub for ADC2 and ADC3#859

burrbull merged 2 commits intostm32-rs:masterstm32-rs/stm32f4xx-hal:masterfrom

harryjwright:fix/adc2-adc3-instance-calibrateharryjwright/stm32f4xx-hal:fix/adc2-adc3-instance-calibrateCopy head branch name to clipboard