Make the ueventd domain enforcing.

All (known) denials have been addressed.

Change-Id: Ic12ed190a2efb7f20be589137a27b95d03dde25a

ueventd.te

 # ueventd seclabel is specified in init.rc since
 # it lives in the rootfs and has no unique file type.
 type ueventd, domain;
-permissive ueventd;
 tmpfs_domain(ueventd)
 write_klog(ueventd)
 security_access_policy(ueventd)