ext4: replace EXT_DEBUG with __maybe_unused in ext4_ext_handle_unwritten_extents()

Replace EXT_DEBUG with __maybe_unused from inside
ext4_ext_handle_unwritten_extents() function.

There should be no functionality change in this patch.
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/ae335b94506cd9db9d2648c1f4dd25a80f9f3ce2.1589086800.git.riteshh@linux.ibm.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -3813,9 +3813,7 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 			struct ext4_ext_path **ppath, int flags,
 			unsigned int allocated, ext4_fsblk_t newblock)
 {
-#ifdef EXT_DEBUG
-	struct ext4_ext_path *path = *ppath;
-#endif
+	struct ext4_ext_path __maybe_unused *path = *ppath;
 	int ret = 0;
 	int err = 0;