Bluetooth: ISO: Shell: Fix underflow of count for TX

The cmd_broadcast and cmd_send both should not take a
count value less than 1.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

Author: Thalley

subsys/bluetooth/host/shell/iso.c

@@ -10,6 +10,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <stddef.h>
 #include <stdlib.h>
 #include <ctype.h>
 #include <zephyr/kernel.h>
@@ -557,6 +558,12 @@ static int cmd_send(const struct shell *sh, size_t argc, char *argv[])
 
 			return -ENOEXEC;
 		}
+
+		if (count < 1) {
+			shell_error(sh, "Cannot send 0 times");
+
+			return -ENOEXEC;
+		}
 	}
 
 	if (!iso_chan.iso) {
@@ -673,6 +680,12 @@ static int cmd_broadcast(const struct shell *sh, size_t argc, char *argv[])
 
 			return -ENOEXEC;
 		}
+
+		if (count < 1) {
+			shell_error(sh, "Cannot send 0 times");
+
+			return -ENOEXEC;
+		}
 	}
 
 	if (!bis_iso_chan.iso) {