spi: rockchip: Resolve unbalanced runtime PM / system PM handling

In the Linux kernel, the following vulnerability has been resolved:

spi: rockchip: Resolve unbalanced runtime PM / system PM handling

Commit e882575efc77 ("spi: rockchip: Suspend and resume the bus during

NOIRQ_SYSTEM_SLEEP_PM ops") stopped respecting runtime PM status and

simply disabled clocks unconditionally when suspending the system. This

causes problems when the device is already runtime suspended when we go

to sleep -- in which case we double-disable clocks and produce a

WARNing.

Switch back to pm_runtime_force_{suspend,resume}(), because that still

seems like the right thing to do, and the aforementioned commit makes no

explanation why it stopped using it.

Also, refactor some of the resume() error handling, because it's not

actually a good idea to re-disable clocks on failure.