perf/x86/intel/uncore: Add Sapphire Rapids server IMC support

The Sapphire Rapids IMC provides the interface to the DRAM and
communicates to the rest of the uncore through the M2M block.

The layout of the control registers for a IMC uncore unit is a little
bit different from the generic one. There is a fixed counter for IMC.
So a specific format and ops are required. Expose the common MMIO ops
which can be reused.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lore.kernel.org/r/1625087320-194204-8-git-send-email-kan.liang@linux.intel.com