Merge tag 'u-boot-stm32-20210113' of https://gitlab.denx.de/u-boot/custodians/u-boot-stm

- Enable logging features for stm32mp15 boards
- Update MAINTAINERS emails for STI and STM32
- Activate OF_LIVE for ST stm32mp15 boards
- Switch to MCO2 for PHY 50 MHz clock for DHCOM boards
- Correction in stm32prog command on uart: always flush DFU on start command
- Update USB-C power detection algorithm on DK boards