spi: change clk_disable_unprepare to clk_unprepare

The corresponding API for clk_prepare is clk_unprepare, other than
clk_disable_unprepare.

Fix this by changing clk_disable_unprepare to clk_unprepare.

Fixes: 5762ab71

 ("spi: Add support for Armada 3700 SPI Controller")
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Link: https://lore.kernel.org/r/20211206101931.2816597-1-mudongliangabcd@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>