drivers: display: ssd16xx: performance improvement

The driver writes the scan entry mode to the display controller on each
set_window call. Multiple calls to set_window can be needed to update
a single frame buffer in the controller.

There's a performance improvement by only setting the scan mode when
the orientation is changed (set_orientation, see previous commit)
and when the profile has changed.
For the latter the scan_mode is lost on the controller
due to a software reset.

Signed-off-by: Sven Depoorter <svndepoorter@gmail.com>