drm/i915: sseu: Use sseu_dev_info in device info

Move all slice/subslice/eu related properties to the sseu_dev_info
struct.

No functional change.

v2:
- s/info/sseu/ based on the new struct name. (Ben)

Reviewed-by: Robert Bragg <robert@sixbynine.org> (v1)
Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1)
Tested-by: Ben Widawsky <benjamin.widawsky@intel.com> (v1)
Signed-off-by: Imre Deak <imre.deak@intel.com>