device_cgroup: Refactor devcgroup_seq_show to use seq_put* helpers

device_cgroup: Refactor devcgroup_seq_show to use seq_put* helpers

Replace set_access(), set_majmin(), and type_to_char() with new helpers
seq_putaccess(), seq_puttype(), and seq_putversion() that write directly
to 'seq_file'.

Simplify devcgroup_seq_show() by hard-coding "a *:* rwm", and use the
new seq_put* helper functions to list the exceptions otherwise.

This allows us to remove the intermediate string buffers while
maintaining the same functionality, including wildcard handling.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>