btrfs: remove unnecessary check of iput argument

iput() already handles NULL and non-NULL parameter, so it is not needed
to check that. This unifies all iput calls.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/relocation.c

@@ -3846,8 +3846,7 @@ out:
 	btrfs_end_transaction(trans);
 	btrfs_btree_balance_dirty(fs_info);
 	if (err) {
-		if (inode)
-			iput(inode);
+		iput(inode);
 		inode = ERR_PTR(err);
 	}
 	return inode;

fs/btrfs/tree-log.c

@@ -894,8 +894,7 @@ update_inode:
 	btrfs_update_inode_bytes(BTRFS_I(inode), nbytes, drop_args.bytes_found);
 	ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
 out:
-	if (inode)
-		iput(inode);
+	iput(inode);
 	return ret;
 }