add dtb support for RPI CM4, CM4s, CM4_ioBoard
Signed-off-by: Klaus Küchemann <maciphone2@googlemail.com>
Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1182
(cherry picked from commit 1bd4f769caf8ffda35477e3c0b2c92348cf2fd5d)