Currently the I3C framework limits SCL frequency to FM speed when
dealing with a mixed slow bus, even if all I2C devices are FM+ capable.
The core was also not accounting for I3C speed limitations when
operating in mixed slow mode and was erroneously using FM+ speed as the
max I2C speed when operating in mixed fast mode.
Fixes: 3a379bbc ("i3c: Add core I3C infrastructure")
Signed-off-by: Vitor Soares <firstname.lastname@example.org>
Cc: Boris Brezillon <email@example.com>
Signed-off-by: Boris Brezillon <firstname.lastname@example.org>