TW_SCREEN_BLANK_ON_BOOT will jolt the screen/touch driver.

If on the default settings the screen will only kick in to action
AFTER it has gone to sleep once and has been woken up again with a
key press, this will be needed to set to 'true' in the
BoardConfig.mk

The code was already there, Dees_Troy and I thought it would be
nice to make it a switch to control at compile time.

Change-Id: I5116a27afe9cba57122761c192ea3ee153d98162