spi: rockchip: Fix clock handling in suspend/resume

The runtime suspend callback might be called by pm domain framework at
suspend_noirq stage. It would try to disable the clocks which already
been disabled by rockchip_spi_suspend.

Call pm_runtime_force_suspend/pm_runtime_force_resume when
suspend/resume to avoid that.

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