authfs: fix lints with rustc 1.51.0

Bug: 184277852
Test: m with rustc 1.51.0
Change-Id: I908bb4c3592e8f824cb9451806e6f8695c8110f6
diff --git a/authfs/src/fsverity/builder.rs b/authfs/src/fsverity/builder.rs
index 94b9718..dd1bd04 100644
--- a/authfs/src/fsverity/builder.rs
+++ b/authfs/src/fsverity/builder.rs
@@ -39,10 +39,7 @@
         .chunks(HASH_PER_PAGE)
         .map(|chunk| {
             let padding_bytes = (HASH_PER_PAGE - chunk.len()) * HASH_SIZE;
-            Ok(Sha256Hasher::new()?
-                .update_from(chunk)?
-                .update(&vec![0u8; padding_bytes])?
-                .finalize()?)
+            Sha256Hasher::new()?.update_from(chunk)?.update(&vec![0u8; padding_bytes])?.finalize()
         })
         .collect()
 }