drm/amdgpu: Set FreeSync state using drm VRR properties

Support for AMDGPU specific FreeSync properties and ioctls are dropped
from amdgpu_dm in favor of supporting drm variable refresh rate
properties.

The notify_freesync and set_freesync_property functions are dropped
from amdgpu_display_funcs.

The drm vrr_capable property is now attached to any DP/HDMI connector.
Its value is updated accordingly to the connector's FreeSync capabiltiy.

The freesync_enable logic and ioctl control has has been dropped in
favor of utilizing the vrr_enabled on the drm CRTC. This allows for more
fine grained atomic control over which CRTCs should support variable
refresh rate.

To handle state changes for vrr_enabled it was easiest to drop the
forced modeset on freesync_enabled change. This patch now performs the
required stream updates when planes are flipped.

This is done for a few reasons:

(1) VRR stream updates can be done in the fast update path

(2) amdgpu_dm_atomic_check would need to be hacked apart to check
    desired variable refresh state and capability before the CRTC
    disable pass.

(3) Performing VRR stream updates on-flip is needed for enabling BTR
    support.

VRR packets and timing adjustments are now tracked and compared to
previous values sent to the hardware.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>