drm/rockchip: Use the helpers for PSR

Instead of rolling our own implementation for tracking when PSR should
be [in]active, use the new self refresh helpers to do the heavy lifting.

Changes in v2:
- updated to reflect changes made in the helpers
Changes in v3:
- use the new atomic hooks to inspect crtc state instead of needing conn state (Daniel)
Changes in v4:
- Use Laurent's get_new_connector_for_encoder helper (Daniel)
- Exit vop disable early if it's already off
Changes in v5:
- Rebase on latest drm-misc-next
- Resolve conflict with s/edp_vsc_psr/dp_sdp/ rename
- Resolve conflict with drm_atomic.h header inclusion

Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190228210939.83386-4-sean@poorly.run
Link to v2: https://patchwork.freedesktop.org/patch/msgid/20190326204509.96515-3-sean@poorly.run
Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-9-sean@poorly.run
Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-9-sean@poorly.run



Cc: Zain Wang <wzz@rock-chips.com>
Cc: Tomasz Figa <tfiga@chromium.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
[seanpaul resolved some conflicts with drmP.h work and Helen's async fixes]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-9-sean@poorly.run