TOMOYO: Return appropriate value to poll().

"struct file_operations"->poll() expects "unsigned int" return value.
All files in /sys/kernel/security/tomoyo/ directory other than
/sys/kernel/security/tomoyo/query and /sys/kernel/security/tomoyo/audit should
return POLLIN | POLLRDNORM | POLLOUT | POLLWRNORM rather than -ENOSYS.
Also, /sys/kernel/security/tomoyo/query and /sys/kernel/security/tomoyo/audit
should return POLLOUT | POLLWRNORM rather than 0 when there is no data to read.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>