drm: Move mode tables to drm_edid.c

The modes are only used from within drm_edid.c so we move them there to
avoid creating duplicates by multiple inclusion of drm_edid_modes.h. As
a side-effect we can also get rid of a few variables that keep track of
the number of entries in the tables and use ARRAY_SIZE() instead.
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>