perf/x86/intel/uncore: Add IMC uncore support for Snow Ridge

IMC uncore unit can only be accessed via MMIO on Snow Ridge.
The MMIO space of IMC uncore is at the specified offsets from the
MEM0_BAR. Add snr_uncore_get_mc_dev() to locate the PCI device with
MMIO_BASE and MEM0_BAR register.

Add new ops to access the IMC registers via MMIO.

Add 3 new free running counters for clocks, read and write bandwidth.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: eranian@google.com
Link: https://lkml.kernel.org/r/1556672028-119221-7-git-send-email-kan.liang@linux.intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>