drm/i915: Support more QGV points

According to BSpec 53998, there is a mask of
max 8 SAGV/QGV points we need to support.

Bumping this up to keep the CI happy(currently
preventing tests to run), until all SAGV
changes land.

v2: Fix second plane where QGV points were
    hardcoded as well.

v3: Change the naming of I915_NUM_SAGV_POINTS
    to be I915_NUM_QGV_POINTS, as more meaningful
    (Ville Syrjälä)

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112189


Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191125160800.14740-1-stanislav.lisovskiy@intel.com


[vsyrjala: Add missing braces around else (checkpatch), fix Bugzilla tag]
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>