ext4: Fix building with EXT4FS_DEBUG

When bg_free_blocks_count was renamed to bg_free_blocks_count_lo in
560671a0, its uses under EXT4FS_DEBUG were not changed to the helper
ext4_free_blks_count.

Another commit, 498e5f24, also did not change everything needed under
EXT4FS_DEBUG, thus making it spill some warnings related to printing
format.

This commit fixes both issues and makes ext4 build again when
EXT4FS_DEBUG is enabled.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 54bf062..e2eab19 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3048,7 +3048,7 @@
 			WARN_ON(ret <= 0);
 			printk(KERN_ERR "%s: ext4_ext_get_blocks "
 				    "returned error inode#%lu, block=%u, "
-				    "max_blocks=%lu", __func__,
+				    "max_blocks=%u", __func__,
 				    inode->i_ino, block, max_blocks);
 #endif
 			ext4_mark_inode_dirty(handle, inode);