Fix warnings in preparation for Rust 1.54.0

This CL fixes several new warnings generated by rustc 1.54.0.

Bug: 194812675
Test: m rust
Change-Id: I3076313ea51c6f4e74029ad9fb45d6f0b6dea460
diff --git a/keystore2/src/remote_provisioning.rs b/keystore2/src/remote_provisioning.rs
index ead24da..40c06e5 100644
--- a/keystore2/src/remote_provisioning.rs
+++ b/keystore2/src/remote_provisioning.rs
@@ -180,7 +180,7 @@
             // and therefore will not be attested.
             Ok(None)
         } else {
-            match self.get_rem_prov_attest_key(&key, caller_uid, db) {
+            match self.get_rem_prov_attest_key(key, caller_uid, db) {
                 Err(e) => {
                     log::error!(
                         concat!(