perf/amd/uncore: Inform the user how many counters each uncore PMU has

Previously, the uncore driver would say "NB counters detected" on F17h
machines, which don't have NorthBridge (NB) counters.  They have Data
Fabric (DF) counters.  Just use the pmu.name to inform users which pmu
to use and its associated counter count.

F17h dmesg BEFORE:

amd_uncore: AMD NB counters detected
amd_uncore: AMD LLC counters detected

F17h dmesg AFTER:

amd_uncore: 4 amd_df counters detected
amd_uncore: 6 amd_l3 counters detected

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200921144330.6331-5-kim.phillips@amd.com