x86, cacheinfo: Disable index in all four subcaches

When disabling an L3 cache index, make sure we disable that index in
all four subcaches of the L3. Clarify nomenclature while at it, wrt to
disable slots versus disable index and rename accordingly.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <1271945222-5283-6-git-send-email-bp@amd64.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>