spi: rockchip: Fix clock handling in remove

We are assuming clocks enabled when calling rockchip_spi_remove, which
is not always true. Those clocks might already been disabled by the
runtime PM at that time.

Call pm_runtime_get_sync before trying to disable clocks to avoid that.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>