drm/i915/skl: Unexport skl_pw1_misc_io_init

drm/i915/skl: Unexport skl_pw1_misc_io_init

On Broxton we need to enable/disable power well 1 during the init/unit
display sequence similarly to Skylake/Kabylake. The code for this will
be added in a follow-up patch, but to prepare for that unexport
skl_pw1_misc_io_init(). It's a simple function called only from a single
place and having it inlined in the Skylake display core init/unit
functions will make it easier to compare it with its Broxton
counterpart.

This also flips the order of Misc IO and power well 1 disabling which
matches the enabling order. The specification doesn't prescribe the
disabling order, so this should be fine.

v2:
- Fix incorrect enable vs. disable power well call in
  skl_display_core_uninit() (Patrik)
- Add commit comment about chaning the order of PW1 and Misc IO power
  well disabling (Patrik)

CC: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459773777-10701-1-git-send-email-imre.deak@intel.com