udf: Verify domain identifier fields

OSTA UDF standard defines that domain identifier in logical volume
descriptor and file set descriptor should contain a particular string
and the identifier suffix contains flags possibly making media
write-protected. Verify these constraints and allow only read-only mount
if they are not met.

Tested-by: Steven J. Magnani <steve@digidescorp.com>
Reviewed-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Jan Kara <jack@suse.cz>