ext4: Remove code handling bio_alloc failure with __GFP_WAIT

Remove code handling bio_alloc failure with __GFP_WAIT.
GFP_NOIO implies __GFP_WAIT.
Signed-off-by: NNikanth Karthikesan <knikanth@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

fs/ext4/extents.c

@@ -2416,8 +2416,6 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
 			len = ee_len;
 
 		bio = bio_alloc(GFP_NOIO, len);
-		if (!bio)
-			return -ENOMEM;
 		bio->bi_sector = ee_pblock;
 		bio->bi_bdev   = inode->i_sb->s_bdev;