perf intel-pt: Fix unassigned instruction op (discovered by MemorySanitizer)

perf intel-pt: Fix unassigned instruction op (discovered by MemorySanitizer)

MemorySanitizer discovered instances where the instruction op value was
not assigned.:

  WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5581c00a76b3 in intel_pt_sample_flags tools/perf/util/intel-pt.c:1527:17
  Uninitialized value was stored to memory at
    #0 0x5581c005ddf8 in intel_pt_walk_insn tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:1256:25

The op value is used to set branch flags for branch instructions
encountered when walking the code, so fix by setting op to
INTEL_PT_OP_OTHER in other cases.

Fixes: 4c761d805bb2d2ea ("perf intel-pt: Fix intel_pt_fup_event() assumptions about setting state type")
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Closes: https://lore.kernel.org/linux-perf-users/20240320162619.1272015-1-irogers@google.com/
Link: https://lore.kernel.org/r/20240326083223.10883-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>