drm/i915/gt: Simplify shmem_create_from_object map_type selection

The object pin created for shmem_create_from_object is just a
single use mapping with the sole purpose of reading the contents
of the whole object in bulk. And the whole source object is also
even a throw-away.  Ergo, the additional logic required by
i915_coherent_map_type can be safely dropped and simplified.
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230801153242.2445478-2-jonathan.cavitt@intel.com
Link: https://patchwork.freedesktop.org/patch/msgid/20230807121957.598420-2-andi.shyti@linux.intel.com

drivers/gpu/drm/i915/gt/shmem_utils.c

@@ -33,7 +33,6 @@ struct file *shmem_create_from_data(const char *name, void *data, size_t len)
 
 struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
 {
-	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	enum i915_map_type map_type;
 	struct file *file;
 	void *ptr;
@@ -44,7 +43,7 @@ struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
 		return file;
 	}
 
-	map_type = i915_coherent_map_type(i915, obj, true);
+	map_type = i915_gem_object_is_lmem(obj) ? I915_MAP_WC : I915_MAP_WB;
 	ptr = i915_gem_object_pin_map_unlocked(obj, map_type);
 	if (IS_ERR(ptr))
 		return ERR_CAST(ptr);