Used script loader is quite useless and hides register numbers
making code hard to understand. Get rid of it and use standard
RegMap register write functions directly.

it913x_priv.h file leaves empty after that change and is also
removed.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>