omapdss doesn't work properly on system suspend. The problem seems to be
the fact that omapdss uses pm_runtime_put() functions when turning off
the hardware, and when system suspend is in process only sync versions
are allowed.

Using non-sync versions normally and sync versions when suspending would
need rather ugly hacks to convey the information of
suspending/not-suspending to different functions. Optimally the driver
wouldn't even need to care about this, and the PM layer would handle
syncing when suspend is in process.

This patch changes all omapdss's pm_runtime_put calls to
pm_runtime_put_sync. This fixes the suspend problem, and probably the
performance penalty of always using sync versions is negligible.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>