ext4: rename ext4_claim_free_blocks() to ext4_claim_free_clusters()

This function really claims a number of free clusters, not blocks, so
rename it so it's clearer what's going on.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 90a3ed7..1c83161 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4297,7 +4297,7 @@
 		 * and verify allocation doesn't exceed the quota limits.
 		 */
 		while (ar->len &&
-			ext4_claim_free_blocks(sbi, ar->len, ar->flags)) {
+			ext4_claim_free_clusters(sbi, ar->len, ar->flags)) {
 
 			/* let others to free the space */
 			yield();