amdgpu: stop using the hash table for fd_tab

We have so few devices that just walking a linked list is probably
faster.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-and-Tested-by: Junwei Zhang <Jerry.Zhang@amd.com>
diff --git a/amdgpu/amdgpu_internal.h b/amdgpu/amdgpu_internal.h
index 99b8ce0..83012ca 100644
--- a/amdgpu/amdgpu_internal.h
+++ b/amdgpu/amdgpu_internal.h
@@ -65,6 +65,7 @@
 
 struct amdgpu_device {
 	atomic_t refcount;
+	struct amdgpu_device *next;
 	int fd;
 	int flink_fd;
 	unsigned major_version;