perf/x86/intel/uncore: Factor out snr_uncore_mmio_map()

The IMC free-running counters on Sapphire Rapids server are also
accessed by MMIO, which is similar to the previous platforms, SNR and
ICX. The only difference is the device ID of the device which contains
BAR address.

Factor out snr_uncore_mmio_map() which ioremap the MMIO space. It can be
reused in the following patch for SPR.

Use the snr_uncore_mmio_map() in the icx_uncore_imc_freerunning_init_box().
There is no box_ctl for the free-running counters.

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/1625087320-194204-14-git-send-email-kan.liang@linux.intel.com