spi: mediatek: add tick_delay support

This patch support tick_delay setting, some users need use
high-speed spi speed, which can use tick_delay to tuning spi clk timing.

Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
Link: https://lore.kernel.org/r/20210713114048.29509-1-mason.zhang@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>