drm/edid: Fix add_cea_modes() style issues

A few styles issues have crept in here, fix them before touching this
code again.

v2: constify arguments that can be (Ville Syrjälä)
v3: constify, but better (Ville Syrjälä)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

diff --cc drivers/gpu/drm/drm_edid.c
Simple merge