drm/i915: update VLV PLL and DPIO code v11

In Valleyview voltage swing, pre-emphasis and lane control registers can
be programmed only through the h/w side band fabric.  Update
vlv_update_pll, i9xx_crtc_enable, and intel_enable_pll with the
appropriate programming.

We need to make sure that the tx lane reset occurs in both the full mode
set and DPMS paths, so factor things out to allow that.

v2: use different DPIO_DIVISOR values for VGA and DisplayPort
v3: Fix update pll logic to use same DPIO_DIVISOR & DPIO_REFSFR values
        for all display interfaces
v4: collapse with various updates
v5: squash with crtc enable/pll enable bits
v6: split out DP code (jbarnes)
    put phyready check under IS_VALLEYVIEW (jbarnes)
    remove unneeded check in 9xx pll div update (Jani)
    wrap VLV pll update call in IS_VALLEYVIEW (Jani)
    move port enable back to end of crtc enable (jbarnes)
    put phyready check under IS_VALLEYVIEW (jbarnes)
v7: fix up conflicts against latest drm-intel-next-queued
v8: use DPIO reg names, fix pipes (Jani)
    from mPhy_registers_VLV2_ww20p5 doc
v9: update to latest info from driver enabling notes doc
    driver_vbios_notes_9
v10: fixup a bit of pipe/port confusion to allow eDP and HDMI to work
     simultaneously (Jesse)
v11: use pll/port callbacks for DPIO port activity (Daniel)
     use separate VLV CRTC enable function (Daniel)
     move around port ready checks (Jesse)

Signed-off-by: Pallavi G <pallavi.g@intel.com>
Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman@intel.com>
Signed-off-by: Gajanan Bhat <gajanan.bhat@intel.com>
Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Drop pfit changes and add a little comment explaining that
vlv has a different enable sequence and so needs it's own crtc_enable
callback. Also apply a fixup patch from Wu Fengguang to shut up some
compiler warnings.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>