xsm: correct AVC lookups for two sysctls

xsm: correct AVC lookups for two sysctls

The current code was incorrectly using SECCLASS_XEN instead of
SECCLASS_XEN2, resulting in the wrong permission being checked.

GET_CPU_LEVELLING_CAPS was checking MTRR_DEL
GET_CPU_FEATURESET was checking MTRR_READ

The default XSM policy only allowed these permissions to dom0, so this
didn't result in a security issue there.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>