drm/i915: Reduce stack usage in debugfs due to SSEU

sseu_dev_info is already a pretty large structure which will likely
continue to grow when future platforms increase potential DSS and EU
counts.  Let's switch the stack placement of this structure in debugfs
with a dynamic allocation.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220315020805.844962-1-matthew.d.roper@intel.com