radeonsi: enable GL4.1 and update documentation (v2)

This enables GL4.1 for radeonsi, and updates the
docs in the correct places.

v2: enable only for llvm 3.7 which has fixes in place.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
3 files changed