samples: net: zperf: Refactor because of timeout overhaul

Convert to use k_timeout_t

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
diff --git a/samples/net/zperf/src/zperf_shell.c b/samples/net/zperf/src/zperf_shell.c
index 1e95c8d..11a8479 100644
--- a/samples/net/zperf/src/zperf_shell.c
+++ b/samples/net/zperf/src/zperf_shell.c
@@ -793,9 +793,10 @@
 	}
 
 	if (argc > 3) {
-		duration_in_ms = K_SECONDS(strtoul(argv[start + 3], NULL, 10));
+		duration_in_ms = MSEC_PER_SEC * strtoul(argv[start + 3],
+							NULL, 10);
 	} else {
-		duration_in_ms = K_SECONDS(1);
+		duration_in_ms = MSEC_PER_SEC * 1;
 	}
 
 	if (argc > 4) {
@@ -912,9 +913,10 @@
 	}
 
 	if (argc > 2) {
-		duration_in_ms = K_SECONDS(strtoul(argv[start + 2], NULL, 10));
+		duration_in_ms = MSEC_PER_SEC * strtoul(argv[start + 2],
+							NULL, 10);
 	} else {
-		duration_in_ms = K_SECONDS(1);
+		duration_in_ms = MSEC_PER_SEC * 1;
 	}
 
 	if (argc > 3) {