drm/i915: Fixup merge of the power well refactor patchset

The wrong v2 version of
drm/i915: Move per-platform power well hooks to intel_display_power_well.c

patch was pushed to drm-intel-next branch instead of v3, fix this up
applying the difference between v2 and v3.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415082524.1826924-1-imre.deak@intel.com