When UMS was deprecated it removed support for nomodeset commandline
we really want this in distro land so we can debug stuff, everyone
should fallback to vesa correctly.

v2: oops -1 isn't used anymore, restore original behaviour
-1 is default, so we can boot with nomodeset on the command line,
then use radeon.modeset=1 to override it for debugging later.

Cc: stable@vger.kernel.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>