In valleyview voltageswing, pre-emphasis and lane control registers can
be programmed only through the h/w side band fabric.
Cleaned up DPLL calculations for Valleyview to support multi display
configurations.
v2: Based on Daniel's feedbacak, moved crt hotplug detect work around as separate
patch. Also moved i9xx_update_pll_dividers to i8xx_update_pll and
i9xx_update_pll.