rust: Fix cargo clippy findings

Fix the new `cargo clippy` findings for updated 1.84 toolchain.

Signed-off-by: Jakob Naucke <naucke@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

rust/pv/src/brcb.rs

@@ -41,7 +41,7 @@ impl TryFrom<Vec<u8>> for BootHdrTags {
 
     fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
         Self::ref_from(&value)
-            .ok_or_else(|| Error::InvBootHdrSize(value.len()))
+            .ok_or(Error::InvBootHdrSize(value.len()))
             .copied()
     }
 }

rust/pv/src/crypto.rs

@@ -361,7 +361,7 @@ pub fn encrypt_aead(
     aad: &[u8],
     conf: &[u8],
 ) -> Result<AeadEncryptionResult> {
-    let tag_len = key.key_type().tag_len().ok_or_else(|| Error::NoAeadKey)?;
+    let tag_len = key.key_type().tag_len().ok_or(Error::NoAeadKey)?;
 
     let nid = key.key_type().into();
     let cipher = Cipher::from_nid(nid).ok_or(Error::UnsupportedCipher(nid))?;