omap3: move check_revision above check_features

omap3_check_revision() does not depend on omap3_check_features()
move this above so that we can add logic based on revision
detected in check_features.

Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Mika Westerberg <mika.westerberg@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>