Revert "drm/radeon: call hpd_irq_event on resume"

Revert "drm/radeon: call hpd_irq_event on resume"

This reverts commit d9ee20c9d3e2e2108eb976e443b3314bfc943c5c.

It turns out that commit can cause problems for systems with multiple
GPUs, and causes X to hang on at least a HP Pavilion dv7 with hybrid
graphics.

This got noticed originally in 4.4.4, where this patch had already
gotten back-ported, but 4.5-rc7 was verified to have the same problem.

Alexander Deucher says:
 "It looks like you have a muxed system so I suspect what's happening is
  that one of the display is being reported as connected for both the
  IGP and the dGPU and then the desktop environment gets confused or
  there some sort problem in the detect functions since the mux is not
  switched to the dGPU.  I don't see an easy fix unless Dave has any
  ideas.  I'd say just revert for now"

Reported-by: Jörg-Volker Peetz <jvpeetz@web.de>
Acked-by: Alexander Deucher <Alexander.Deucher@amd.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: stable@kernel.org  # wherever d9ee20c9d3e2 got back-ported
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>