spi: tegra20-slink: add missed clk_unprepare

[ Upstream commit 04358e40ba96d687c0811c21d9dede73f5244a98 ]

The driver misses calling clk_unprepare in probe failure and remove.
Add the calls to fix it.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Link: https://lore.kernel.org/r/20191115083122.12278-1-hslester96@gmail.com


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