x86/intel_rdt: Introduce RDT resource group mode

At this time there are no constraints on how bitmasks represented by
schemata can be associated with closids represented by resource groups.  A
bitmask of one class of service can without any objections overlap with the
bitmask of another class of service.

The concept of "mode" is introduced in preparation for support of control
over whether cache regions can be shared between classes of service. At
this time the only mode reflects the current cache allocations where all
can potentially be shared.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/87e88275597fbfa03ea9d41c1186bf012c831c01.1529706536.git.reinette.chatre@intel.com