drm: use idr_init_base() to initialize master->magic_map

idr_init_base(), implemented by commit 6ce711f2 ("idr: Make 1-based
IDRs more efficient"), let us set an arbitrary base other than
idr_init(), which uses base 0.

Since, for this IDR, no ID < 1 is ever requested/allocated, using
idr_init_base(&idr, 1) avoids unnecessary tree walks.
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220701185303.284082-4-dakr@redhat.com

drivers/gpu/drm/drm_auth.c

@@ -140,7 +140,7 @@ struct drm_master *drm_master_create(struct drm_device *dev)
 
 	kref_init(&master->refcount);
 	drm_master_legacy_init(master);
-	idr_init(&master->magic_map);
+	idr_init_base(&master->magic_map, 1);
 	master->dev = dev;
 
 	/* initialize the tree of output resource lessees */