drm/i915: Fix and cleanup DPLL calculation for Ironlake
drm/i915: Fix and cleanup DPLL calculation for Ironlake

When the ideal error range can't be reached, this will safely use
a most closed one. Clean up some dumb codes in DPLL function too.

This fixes DPLL clock issue against one monitor at 1680x1050@60hz.

Signed-off-by: Zhenyu Wang <2be145655f058b1e18fb2a9466bd2b1b12e2cd7e@linux.intel.com>
Signed-off-by: Eric Anholt <96f164ad4d9b2b0dacf8ebee2bb1eeb3aa69adf1@anholt.net>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs