drm/i915/panel: Split range scaling calculation for readiblity

Split the 64b multiplication from the division so that it doesn't sprawl
across a couple of lines and use mul_u32_u32() instead of open-coding
the 64b conversion.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180214091747.12753-2-chris@chris-wilson.co.uk
1 file changed