drm/edid: convert get_monitor_name() to drm_edid

We'll need to propagate drm_edid everywhere.

v2: Drop incorrect NULL name check (Dan Carpenter)

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c940aad14f323ef3a7907a0fb534011deb1589a9.1652097712.git.jani.nikula@intel.com