drm/i915/pxp: load the pxp module when we have a gsc-loaded huc

The mei_pxp module is required to send the command to load authenticate
the HuC to the GSC even if pxp is not in use for protected content
management.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220928004145.745803-8-daniele.ceraolospurio@intel.com