perf mem: Fix printing PERF_MEM_LVLNUM_{L2_MHB|MSC}

With commit 8ec9497d ("tools/include: Sync uapi/linux/perf.h
with the kernel sources"), 'perf mem report' gives an incorrect memory
access string.
...
0.02%	1	3644	L5 hit	[.] 0x0000000000009b0e	mlc	[.] 0x00007fce43f59480
...

This occurs because, if no entry exists in mem_lvlnum, perf_mem__lvl_scnprintf
will default to 'L%d, lvl', which in this case for PERF_MEM_LVLNUM_L2_MHB is 0x05.
Add entries for PERF_MEM_LVLNUM_L2_MHB and PERF_MEM_LVLNUM_MSC to mem_lvlnum,
so that the correct strings are printed.
...
0.02%	1	3644	L2 MHB hit	[.] 0x0000000000009b0e	mlc	[.] 0x00007fce43f59480
...

Fixes: 8ec9497d ("tools/include: Sync uapi/linux/perf.h with the kernel sources")
Suggested-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Link: https://lore.kernel.org/r/20240926144040.77897-1-thomas.falcon@intel.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>