btrfs: Fix bool initialization/comparison

Bool initializations should use true and false. Bool tests don't need
comparisons.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index aafcc78..7994505 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2046,7 +2046,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	struct btrfs_trans_handle *trans;
 	struct btrfs_log_ctx ctx;
 	int ret = 0, err;
-	bool full_sync = 0;
+	bool full_sync = false;
 	u64 len;
 
 	/*