Merge tag 'u-boot-stm32-20210727' of https://source.denx.de/u-boot/custodians/u-boot-stm

- FIP Enable OP-TEE and TZC support in SPL for STM32MP15 SoC
- Add stm32mp15 missing SPI clock support
- Manage pull-up on gpio button STM32MP15 boards
- Correct STM32MP15 boot when TAMPER registers are invalid
- Fix EMMC pinmux on STM32MP15 Avenger96 board