spi: fsl-dspi: add missing clk_disable_unprepare() in dspi_remove()

clock source is prepared and enabled by clk_prepare_enable()
in probe function, but no disable or unprepare in remove.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NMark Brown <broonie@linaro.org>

drivers/spi/spi-fsl-dspi.c

@@ -536,6 +536,7 @@ static int dspi_remove(struct platform_device *pdev)
 
 	/* Disconnect from the SPI framework */
 	spi_bitbang_stop(&dspi->bitbang);
+	clk_disable_unprepare(dspi->clk);
 	spi_master_put(dspi->bitbang.master);
 
 	return 0;