spi: pl022: Don't ignore power domain and amba bus at system suspend

Previously only the resources controlled by the driver were put into
low power state at system suspend. Both the amba bus and a potential
power domain were ignored.

Moreover, while putting the device into low power state we first
brought it back to full power, but for no particular reason.

To handle both issues above, use pm_runtime_force_suspend|resume() from
the system suspend|resume callbacks.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>