spi/pl022: Minor simplification for runtime pm

In probe pm_runtime_put_autosuspend has the same effect as doing
pm_runtime_put. This due to upper layer in driver core is preventing
the device from being runtime suspended by a pm_runtime_get*.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>