f2fs: fix 32-bit build

The addition of multiple-device support broke CONFIG_BLK_DEV_ZONED
on 32-bit machines because of a 64-bit division:

fs/f2fs/f2fs.o: In function `__issue_discard_async':
extent_cache.c:(.text.__issue_discard_async+0xd4): undefined reference to `__aeabi_uldivmod'

Fortunately, bdev_zone_size() is guaranteed to return a power-of-two
number, so we can replace the % operator with a cheaper bit mask.

Fixes: 792b84b74b54 ("f2fs: support multiple devices")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -693,7 +693,8 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
 	}
 	sector = SECTOR_FROM_BLOCK(blkstart);
 
-	if (sector % bdev_zone_size(bdev) || nr_sects != bdev_zone_size(bdev)) {
+	if (sector & (bdev_zone_size(bdev) - 1) ||
+				nr_sects != bdev_zone_size(bdev)) {
 		f2fs_msg(sbi->sb, KERN_INFO,
 			"(%d) %s: Unaligned discard attempted (block %x + %x)",
 			devi, sbi->s_ndevs ? FDEV(devi).path: "",