Fix it for ES3.0. Also use ES3.0 now as the default for unknown
future revision, and make the code easier to follow.

Also fixed omap detection for ES2.1 and ES3.0 with a patch from
Tero Kristo.
Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>