spi: coldfire-qspi: Use clk_prepare_enable and clk_disable_unprepare

Convert clk_enable() to clk_prepare_enable() and clk_disable() to
clk_disable_unprepare() respectively in the spi-coldfire-qspi.c.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Link: https://lore.kernel.org/r/1594790807-32319-2-git-send-email-zhangqing@loongson.cn


Signed-off-by: Mark Brown <broonie@kernel.org>