The RTEMS Software Engineering Guide specifies that the SPDX license
annotation shouldbe the first line of the file and not part of the
copyright/license comment block.
- Refactor the pl011 driver to be extensible.
- Add IRQ support and baudrate configuration support for pl011 driver.
- Modify related BSP.
- Add doxygen comments for arm-pl011.
Close#5026
Co-authored-by: Ning Yang <yangn0@qq.com>
