drm/radeon: fix bank information in tiling config

commit 29d654067a98c1cb8874c774e5fd799a038af8a6 upstream.

While there are cards with more than 8 mem banks, the max
number of banks from a tiling perspective is 8, so cap
the tiling config at 8 banks.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=43448

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 drm/radeon: fix HD6790, HD6570 backend programming

Without this bit sets we get broken rendering and
lockups.

fglrx sets this bit.

Bugs that should be fixed by this patch :
https://bugs.freedesktop.org/show_bug.cgi?id=49792
https://bugzilla.kernel.org/show_bug.cgi?id=43207
https://bugs.freedesktop.org/show_bug.cgi?id=39282

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

"Credit gregkh"