hwpmc/amd: replace static pmcdesc[] and pc_amdpmcs[] with dynamic allocationHEADmain

AMD_NPMCS_MAX = 342 (16 core + 6 L3 + 64 DF + 256 UMC). On a Zen 4
EPYC 9654 with 6 core, 6 L3, 16 DF, and 4 UMC counters, only 32
descriptors are needed; the static arrays over-allocate by ~10x.

Replace both amd_pmcdesc[AMD_NPMCS_MAX] and per-CPU pc_amdpmcs[AMD_NPMCS_MAX]
with mallocarray() sized to the actual registered PMC count:
  - amd_pmcdesc: allocated in pmc_amd_initialize()
  - pc_amdpmcs:  allocated per-CPU in amd_pcpu_init(), freed in fini()

Normalize amd_l3_npmcs and amd_df_npmcs against the AMDID2_PTSCEL2I
and AMDID2_PNXC feature bits before computing npmcs_total, so that
allocation, registration, and amd_get_msr() row offsets are all derived
from the same values.  Previously the ternary in npmcs_total excluded
L3/DF from the allocation while the globals retained their defaults,
causing amd_get_msr() to miscompute DF row offsets when L3 is absent.

amd_umc_npmcs comes from CPUID Fn8000_0022h EBX[23:16] (NumUMCCounters)
and is zero when the leaf is absent, so no additional feature flag is
needed.  See AMD64 APM Vol.3 Appendix E.

Fix three error-path memory leaks: amd_hwcheck() failure, goto error,
and finalize.  Reset amd_npmcs = 0 on the error path.

Tested on AMD EPYC 9654 (Zen 4, Family 19h Model 11h, 192 threads).
Full PMC test suite (IBS/UMCDF/PMC/L3/DF/TSC): 0 failures.

Signed-off-by: Osvaldo Janeri Filho <ojanerif@amd.com>
Reviewed by:	mhorne
MFC after:	1 week
Sponsored by:	AMD
Pull Request:	https://github.com/freebsd/freebsd-src/pull/2415

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