drm/panthor: Don't check the array stride on empty uobj arrays

The user is likely to leave all the drm_panthor_obj_array fields
to zero when the array is empty, which will cause an EINVAL failure.

v2:
- Added R-bs

Fixes: 4bdca115 ("drm/panthor: Add the driver frontend block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240703071640.231278-2-boris.brezillon@collabora.com

drivers/gpu/drm/panthor/panthor_drv.c

@@ -86,15 +86,15 @@ panthor_get_uobj_array(const struct drm_panthor_obj_array *in, u32 min_stride,
 	int ret = 0;
 	void *out_alloc;
 
+	if (!in->count)
+		return NULL;
+
 	/* User stride must be at least the minimum object size, otherwise it might
 	 * lack useful information.
 	 */
 	if (in->stride < min_stride)
 		return ERR_PTR(-EINVAL);
 
-	if (!in->count)
-		return NULL;
-
 	out_alloc = kvmalloc_array(in->count, obj_size, GFP_KERNEL);
 	if (!out_alloc)
 		return ERR_PTR(-ENOMEM);