lib/igt_fb: Round to nearest when clamping rgb

I think round to nearest is maybe more correct here. Also do the
clamp with integers as it actually makes the resulting code
measurably faster.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
1 file changed