tty: serial: meson: Describes the calculation of the UART baud rate clock using a clock frame

Using the common Clock code to describe the UART baud rate clock
makes it easier for the UART driver to be compatible with the
baud rate requirements of the UART IP on different meson chips.

Signed-off-by: Yu Tu <yu.tu@amlogic.com>
Link: https://lore.kernel.org/r/20220225073922.3947-4-yu.tu@amlogic.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>