Hide sys_rawio SELinux denials.

We often see the following denials:

avc: denied { sys_rawio } for comm="update_engine" capability=17 scontext=u:r:update_engine:s0 tcontext=u:r:update_engine:s0 tclass=capability permissive=0
avc: denied { sys_rawio } for comm="boot@1.0-servic" capability=17 scontext=u:r:hal_bootctl_default:s0 tcontext=u:r:hal_bootctl_default:s0 tclass=capability permissive=0

These are benign, so we are hiding them.

Bug: 37778617
Test: Boot device.
Change-Id: Iac196653933d79aa9cdeef7670076f0efc97b44a