btrfs: fix string and comment grammatical issues and typos

Signed-off-by: Nicholas D Steeves <nsteeves@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c
index 91feb2b..b1434bb 100644
--- a/fs/btrfs/ulist.c
+++ b/fs/btrfs/ulist.c
@@ -28,7 +28,7 @@
  * }
  * ulist_free(ulist);
  *
- * This assumes the graph nodes are adressable by u64. This stems from the
+ * This assumes the graph nodes are addressable by u64. This stems from the
  * usage for tree enumeration in btrfs, where the logical addresses are
  * 64 bit.
  *