Updating of Cache and Memory bandwidth QOS MSRs is different.

Add a function pointer to struct rdt_resource and convert the cache part
over.

Based on Vikas all in one patch^Wmess.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: vikas.shivappa@intel.com