anv: Fix handling of host_cached_coherent bos in gen9 lp in older kernels

anv: Fix handling of host_cached_coherent bos in gen9 lp in older kernels

Kernel versions without DRM_I915_QUERY_MEMORY_REGIONS support will
take a different code path in i915_gem_create() that lacks the
i915_gem_set_caching() call to make cached bos in gen9 lp 1 way
coherent.

Fixes: fc0acf6d90 ("anv: Move i915 specific gem_set_caching to backend")
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26457>
(cherry picked from commit 0eac6298f2eb3030f53ec508af87f0c4488b20cb)