tools lib subcmd: Fix missing member name

tools lib subcmd: Fix missing member name

This patch adds missing member names to struct initializations.

Although in C99 for struct S {int x, int y} two init codes struct S s =
{.x = (a), (b)} and struct S s = {.x = (a), .y = (b)} are the same, it
is better to explicitly write .y (.argh in this patch) for readability
and robustness against language/compiler evolutions.

Signed-off-by: Soramichi Akiyama <akiyama@m.soramichi.jp>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170113215623.32fb1ac2d862af0048c30fe6@m.soramichi.jp
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>