btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit

[ Upstream commit 020e5277 ]

Commit 2efc459d ("sysfs: Add sysfs_emit and sysfs_emit_at to format
sysfs out") merged in 5.10 introduced two new functions sysfs_emit() and
sysfs_emit_at() which are aware of the PAGE_SIZE limit of the output
buffer.

Use the above two new functions instead of scnprintf() and snprintf()
in various sysfs show().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: fca432e7 ("btrfs: sysfs: fix direct super block member reads")
Signed-off-by: Sasha Levin <sashal@kernel.org>