serial: sccnxp: Using CLK API for getting UART clock

This patch removes "frequency" parameter from SCCNXP platform_data
and uses CLK API for getting clock. If CLK ommited, default IC
frequency will be used instead.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc arch/mips/sni/a20r.c
Simple merge

diff --cc drivers/tty/serial/sccnxp.c
Simple merge

diff --cc include/linux/platform_data/serial-sccnxp.h
Simple merge