drm/i915/hsw+: Add has_fuses power well attribute

drm/i915/hsw+: Add has_fuses power well attribute

The pattern of a power well backing a set of fuses whose initialization
we need to wait for during power well enabling is common to all GEN9+
platforms. Adding support for this to the HSW power well enable helper
allows us to use the HSW/BDW power well code for GEN9+ as well in a
follow-up patch.

v2:
- Use an enum for power gates instead of raw numbers. (Ville)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170711204236.5618-6-imre.deak@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>