hs20-osu-client: Hide a trivial compiler warning

This patch hides a compiler warning:

osu_client.c: In function ‘cmd_osu_select’:
osu_client.c:2200:2: warning: ‘osu_count’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  for (i = 0; i < osu_count; i++) {
  ^

osu_count is actually initialized in parse_osu_providers() if non-NULL
value is returned.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>

hs20/client/osu_client.c

@@ -2134,7 +2134,7 @@ static int cmd_osu_select(struct hs20_osu_client *ctx, const char *dir,
 	char fname[255];
 	FILE *f;
 	struct osu_data *osu = NULL, *last = NULL;
-	size_t osu_count, i, j;
+	size_t osu_count = 0, i, j;
 	int ret;
 
 	write_summary(ctx, "OSU provider selection");