btrfs: sysfs: export supported checksums

Export supported checksum algorithms via sysfs.

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>

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Changes to v2:
- Prevent possible overflow of sysfs attribute
Changes to v1:
- Removed btrfs_checksums_store() function (Nik)
- Renamed sysfs file to supported_checksums
1 file changed