USB: atm: ueagle-atm: fix up some permissions on the sysfs files

Some of the sysfs files had the incorrect permissions.  Some didn't make
sense at all (writable for a file that you could not write to?)

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: Damien Bergamini <damien.bergamini@free.fr>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>