drm/i915: Clear pipe's pll hw state in hsw_dp_set_ddi_pll_sel()
drm/i915: Clear pipe's pll hw state in hsw_dp_set_ddi_pll_sel()

Similarly to what is done for SKL, clear the dpll_hw_state of the pipe
config in hsw_dp_set_ddi_pll_sel(), since it main contain stale values.
That can happen if a crtc that was previously driving an HDMI connector
switches to a DP connector. In that case, the wrpll field was left with
its old value, leading to warnings like the one below:

[drm:check_crtc_state [i915]] *ERROR* mismatch in dpll_hw_state.wrpll (expected 0xb035061f, found 0x00000000)
------------[ cut here ]------------
WARNING: CPU: 1 PID: 767 at drivers/gpu/drm/i915/intel_display.c:12324 check_crtc_state+0x975/0x10b0 [i915]()
pipe state doesn't match!

This regression was indroduced in

commit dd3cd74acf12723045a64f1f2c6298ac7b34a5d5
Author: Ander Conselvan de Oliveira <71330eafc99ba196752d2b2af84b34019e4104c2@intel.com>
Date:   Fri May 15 13:34:29 2015 +0300

    drm/i915: Don't overwrite (e)DP PLL selection on SKL

Reported-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Signed-off-by: Ander Conselvan de Oliveira <71330eafc99ba196752d2b2af84b34019e4104c2@intel.com>
Tested-by: Jani Nikula <ba783f3beccaedfda693f41a15407d612a629408@intel.com>
Reviewed-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>
Signed-off-by: Jani Nikula <ba783f3beccaedfda693f41a15407d612a629408@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs