sparc64: Setup a scheduling domain for highest level cache.

sparc64: Setup a scheduling domain for highest level cache.

Individual scheduler domain should consist different hierarchy
consisting of cores sharing similar property. Currently, no
scheduler domain is defined separately for the cores that shares
the last level cache. As a result, the scheduler fails to take
advantage of cache locality while migrating tasks during load
balancing.

Here are the cpu masks currently present for sparc that are/can
be used in scheduler domain construction.
cpu_core_map : set based on the cores that shares l1 cache.
core_core_sib_map : is set based on the socket id or max cache id.
The prior SPARC notion of socket was defined as highest level of
shared cache. However, the MD record on T7 platforms now describes
the CPUs that share the physical socket and this is no longer tied
to shared cache.

That's why a separate cpu mask needs to be created that truly
represent highest level of shared cache for all platforms.

Modified after cherry picked from upstream commit.
d624716b6c67e60681180786564b92ddb521148a
The implementation is largely based on Chris's patches.

Signed-off-by: Atish Patra <atish.patra@oracle.com>
Reviewed-by: Chris Hyser <chris.hyser@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 1e655ca52bb2727471f20cf4d8f62b4b9f69e6fc)
Signed-off-by: Allen Pais <allen.pais@oracle.com>