stats: Remove warnings about never read variables

Nothing is being done with these return values. Remove them
for now and update the TODO entry that is present at two of
the three places.

stats.c: In function ‘rate_ctr_handler’:
stats.c:570:6: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]
  int rc;
      ^
stats.c: In function ‘osmo_stat_item_handler’:
stats.c:617:6: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]
  int rc;
      ^
stats.c: In function ‘handle_counter’:
stats.c:651:6: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]
  int rc;

0 files changed, 0 insertions, 0 deletions