spi core: stop updating dev->power.power_state

Don't update dev->power.power_state any more in the SPI core.  The only
reason to update this scheduled-to-be-removed field was to make the
already-removed /sys/devices/.../power/state files work better.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>