intel/drm-shim: Return correct values for I915_PARAM_HAS_ALIASING_PPGTT

intel/drm-shim: Return correct values for I915_PARAM_HAS_ALIASING_PPGTT

It sure looks like it should be a Boolean value, but it's not.  The
values that we really want for later platforms are either 2 or 3.  The
old intel_stub.c in shader-db just always returns 3
(I915_GEM_PPGTT_FULL).  This returns the same set of values per platform
that kernel 5.6.13 would.

When using the shim for ICL with i965 driver, this fixes:

    i965 requires softpin (Kernel 4.5) on Gen10+.

Fixes: 0f4f1d70bfe ("intel: add stub_gpu tool")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5061>