drm/amdgpu: use idr_init_base() to initialize mgr->ctx_handles

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, 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/20220701185303.284082-2-dakr@redhat.com

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c

@@ -842,7 +842,7 @@ void amdgpu_ctx_mgr_init(struct amdgpu_ctx_mgr *mgr,
 
 	mgr->adev = adev;
 	mutex_init(&mgr->lock);
-	idr_init(&mgr->ctx_handles);
+	idr_init_base(&mgr->ctx_handles, 1);
 
 	for (i = 0; i < AMDGPU_HW_IP_NUM; ++i)
 		atomic64_set(&mgr->time_spend[i], 0);