board/BuR/tseries: take usage of CONFIG_LCD_ROTATION

We take use of the new LCD_ROTATION feature.
The information about how the display is rotated is taken from B&R specific
(/factory-settings/rotation) information in the devicetree.

The information there is stored as string (cw, ud, ccw, none) since starting
support of this devices and cannot be changed, so we have to convert it into

none = 0
cw   = 1
ud   = 2
ccw  = 3

Signed-off-by: Hannes Petermaier <oe5hpm@oevsv.at>