fbcon: fbcon_is_inactive() -> fbcon_is_active()

Invert fbcon_is_inactive() into fbcon_is_active(). Much easier
on the poor brain when you don't have to do dobule negations
all over the place.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Helge Deller <deller@gmx.de>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>