BACKPORT: LSM: Remove unused capability.c

BACKPORT: LSM: Remove unused capability.c

The stub functions in capability.c are no longer required
with the list based stacking mechanism. Remove the file.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
(cherry-picked from upstream 1ddd3b4e07a4be9fe3f1ce2441b01859154f4358)