lsm: rework lsm_active_cnt and lsm_idlist[]

lsm: rework lsm_active_cnt and lsm_idlist[]

Move the LSM active count and lsm_id list declarations out of a header
that is visible across the kernel and into a header that is limited to
the LSM framework.  This not only helps keep the include/linux headers
smaller and cleaner, it helps prevent misuse of these variables.

Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johhansen@canonical.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>