block: Implement DiskFile marker trait for RawFileDisk

Add empty disk_file::DiskFile impl for RawFileDisk. This
marker supertrait requires DiskSize + Geometry + Sync, all
of which are now satisfied.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

block/src/raw_async.rs

@@ -119,6 +119,8 @@ impl disk_file::Resizable for RawFileDisk {
     }
 }
 
+impl disk_file::DiskFile for RawFileDisk {}
+
 pub struct RawFileAsync {
     fd: RawFd,
     io_uring: IoUring,