wfa_dut: Eliminate warning on snprintf buffer len

BUG=b:162914250
TEST=python simple_console.py sta_get_info,interface,wlan0

Change-Id: Ia5a1857e3dcfebd74790c7289c2b397c6035ba18
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/Wi-FiTestSuite-Linux-DUT/+/2475214
Tested-by: Wojciech Jakóbczyk <wja@semihalf.com>
Reviewed-by: Shuo-Peng Liao <deanliao@chromium.org>
diff --git a/lib/wfa_cs.c b/lib/wfa_cs.c
index 4f3a14a..ff3d698 100644
--- a/lib/wfa_cs.c
+++ b/lib/wfa_cs.c
@@ -1197,7 +1197,7 @@
   dutCmdResponse_t infoResp;
   dutCommand_t* getInfo = (dutCommand_t*)caCmdBuf;
   FILE* tmpfd;
-  char vendor[256];
+  char vendor[80];
   const char* vendorFileName = "/tmp/ifvendor.txt";
 
   sprintf(gCmdStr, "getifvendor.sh %s %s\n", getInfo->intf, vendorFileName);
@@ -1215,7 +1215,7 @@
   /* open the output result and scan/retrieve the info */
   tmpfd = fopen(vendorFileName, "r+");
 
-  if (tmpfd == NULL || fgets(vendor, 256, tmpfd) == NULL) {
+  if (tmpfd == NULL || fgets(vendor, sizeof(vendor), tmpfd) == NULL) {
     infoResp.status = STATUS_ERROR;
     wfaEncodeTLV(WFA_STA_GET_INFO_RESP_TLV, sizeof(infoResp.status),
                  (BYTE*)&infoResp, respBuf);