benchmarks/osperf: fix warning maybe-uninitialized

[crafcat7]

Summary

Fix osperf build warning

In function 'performance_gettime',
    inlined from 'hpwork_performance' at osperf.c:245:10:
osperf.c:123:3: error: 'result.end' may be used uninitialized [-Werror=maybe-uninitialized]
  123 |   up_perf_convert(result->end - result->start, &ts);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
osperf.c: In function 'hpwork_performance':
osperf.c:228:29: note: 'result.end' was declared here
  228 |   struct performance_time_s result;
      |                             ^~~~~~
CC:  audio/lib_buffer.c
CC:  common/arm64_initialize.c
CC:  builtin/lib_builtin_getname.c

Impact

• Build: fix warnings.
• Runtime: initialize memory before use.

Testing

Local build success

[jerpelea]

please update title to
benchmarks/osperf: fix warning maybe-uninitialized

[crafcat7]

please update title to benchmarks/osperf: fix warning maybe-uninitialized

Done

[cederom]

Thank you @crafcat7 :-)