spi: coldfire-qspi: Use clk_disable_unprepare in the remove function

spi: coldfire-qspi: Use clk_disable_unprepare in the remove function

'clk_prepare_enable()' is used in the probe, so 'clk_disable_unprepare()'
should be used in the remove function to be consistent.

Fixes: 499de01c5c0b ("spi: coldfire-qspi: Use clk_prepare_enable and clk_disable_unprepare")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/ee91792ddba61342b0d3284cd4558a2b0016c4e7.1629319838.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Mark Brown <broonie@kernel.org>