security: remove EARLY_LSM_COUNT which never used

This macro is never used from it was introduced in commit e6b1db98
("security: Support early LSMs"), better to remove it.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: James Morris <jmorris@namei.org>