kernel: remove permissive_or_unconfined()

Change-Id: If414cf8d973270a91628d64442a6d82e546f18f3
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

kernel.te

 # Life begins with the kernel.
 type kernel, domain;
-permissive_or_unconfined(kernel)
 
 allow kernel self:capability sys_nice;