PM / devfreq: tegra30: Disable clock on error in probe

This error path needs to call clk_disable_unprepare().

Fixes: 7296443b ("PM / devfreq: tegra30: Handle possible round-rate error")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>