During system suspend, at the time DSS is being suspended, SPI is
already suspended and it's clocks are cut. Because of this trying to
communicate with the LCD controller results in a deadlock.

To fix this, split out LCD programming parts of display enable/disable
functions and perform them from SPI PM callbacks instead when system is
being suspended. If the display is just being enabled/disabled, do it
from DSS callbacks as before.
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>