perf annotate-data: Add variable_state_str()

perf annotate-data: Add variable_state_str()

So that it can show a proper debug message in the right place.  The
check_variable() is used in other places which don't want to print the
message.

  $ perf --debug type-profile annotate --data-type

Before:
  -----------------------------------------------------------
  find data type for 0x140(reg14) at update_blocked_averages+0x2db
  CU for kernel/sched/fair.c (die:0x12dd892)
  frame base: cfa=1 fbreg=7
  no pointer or no type                                         <<<--- removed
  check variable "__mptr" failed (die: 0x13022f1)
   variable location: base=reg14, offset=0x140
   type='void*' size=0x8 (die:0x12dd8f9)

After:
  -----------------------------------------------------------
  find data type for 0x140(reg14) at update_blocked_averages+0x2db
  CU for kernel/sched/fair.c (die:0x12dd892)
  frame base: cfa=1 fbreg=7
  found "__mptr" (die: 0x13022f1) in scope=4/4 (die: 0x13022e8) failed: no/void pointer  <<<--- here
   variable location: base=reg14, offset=0x140
   type='void*' size=0x8 (die:0x12dd8f9)

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240816235840.2754937-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>