drm/i915/icl: Fix power well anonymous union initializers

Similarly to commit 0a445945
("drm/i915: Work around GCC anonymous union initialization bug")
we need to initialize anonymous unions inside extra braces to work
around a GCC4.4 build error.

v2:
- Fix checkpatch errors in commit log. (Paulo)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180806095843.13294-2-imre.deak@intel.com