ext4: remove comment code ext4_discard_preallocations

Just remove comment code in ext4_discard_preallocations.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230303172120.3800725-20-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mballoc.c

@@ -4926,7 +4926,6 @@ void ext4_discard_preallocations(struct inode *inode, unsigned int needed)
 	int err;
 
 	if (!S_ISREG(inode->i_mode)) {
-		/*BUG_ON(!list_empty(&ei->i_prealloc_list));*/
 		return;
 	}