drm/radeon: Use direct mapping for fast fb access on RS690

This patch allows the CPU to map the stolen vram segment
directly rather than going through the PCI BAR. This
significantly improves performance for certain workloads with
a properly patched ddx.

Use radeon.fastfb=1 to enable it (disabled by default).
Currently only supported on RS690, but support for RS780/880
and newer APUs may be added eventually.

Signed-off-by: Samuel Li <samuel.li@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/radeon/kms: display watermark updates (v2)

- Add module option to force the display priority
0 = auto, 1 = normal, 2 = high
- Default to high on r3xx/r4xx/rv515 chips
Fixes flickering problems during heavy acceleration
due to underflow to the display controllers
- Fill in minimal support for RS600

v2 - update display priority when bandwidth is updated
so the user can change the parameter at runtime and it
will take affect on the next modeset.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drm/radeon/kms: Convert RS690/RS740 to new init path (V2).

Also cleanup register specific to RS690/RS740. Version 2 add
missing header file for register, remove unecessary call to AGP
function and fix an indentation bug.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>