drm/i915/skl: don't toggle PW1 and MISC power wells on-demand

drm/i915/skl: don't toggle PW1 and MISC power wells on-demand

With the DMC firmware installed we don't need to handle HW resources
that are handled automatically by the firmware. Besides being redundant
this can also interfere with the firmware, possibly getting it into a
broken/blocked state. The on-demand handling of PW1 was already half-way
removed, MISC IO was still handled in this way. After the last patch we
init/uninit these HW resources manually as part of the display core
init/uninit sequence, so we can now remove the on-demand handling for
these completely.

We still keep around the power wells (with no domains attached to them)
since the manual toggling during display core init/uninit happens via
the current API.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
[s/beeing/being/ in commit message (imre)]
Link: http://patchwork.freedesktop.org/patch/msgid/1446657859-9598-7-git-send-email-imre.deak@intel.com