Various improvements

• linux-stm32mp kernel improvements
  • add USB SIO adapter driver based on CP120x to default kernel config
  • add SPI-CAN MCP251XFD driver to default kernel config
  • stm32mp-t1000 SOM device tree: Add gpio pin hook
  • spi_ks8895, ti-sn65dsi83: Fix drivers to allow gpio operations to sleep
  • spi_ks8895 ethernet switch: Add delay before starting spi communication after reset
• u-boot-stm32mp improvements
  • Enables u-boot option to set the default value for 'board_name' environment variable in defconfig file
• tf-a-stm32mp improvements
  • switch kernel clock for spi2 and spi3 from 50MHz to 200MHz
• Add license and readme files
• image-ktn-test
  • adapt for stm32mp1