drm/i915: run hsw_disable_pc8() later on resume

We want to run intel_uncore_early_sanitize() before we touch any
registers, because on BDW, when we resume, the FPGA_DBG_RM_NOCLAIM bit
is set, so we need to clear it - through intel_uncore_early_sanitize()
- before we do anything else. With the current code, we don't clear
the bit before our first register access, so we print a WARN
complaining about an unclaimed register error.

v1: Was called "drm/i915: run intel_uncore_early_sanitize earlier on
resume"
v2: Was called "drm/i915: run intel_uncore_early_sanitize earlier on
resume on non-VLV"
v3: This one, on top of the intel_resume_prepare() rework.
v4: Rebase.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>