dfu: Add optional timeout parameter

When the `dfu` command is called from the U-Boot environment,
it now accepts an optional parameter that specifies a timeout (in seconds).
If a DFU connection is not made within that time the `dfu` command exits
(as it would if Ctrl+C was pressed). If the timeout is left empty or being
zero the `dfu` command behaves as it does now.

This is useful for allowing U-Boot to check to see if anything wants to
upload new firmware before continuing to boot.

The patch is based on the commit
https://github.com/01org/edison-u-boot/commit/5e966ccc3c65c18c9783741fa04e0c45e021780c
by Sebastien Colleur, which has been heavily reworked due to U-Boot changes
in the past.

Signed-off-by: Brad Campbell <bradjc5@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
diff --git a/cmd/dfu.c b/cmd/dfu.c
index 14a8ec8..b30f8a5 100644
--- a/cmd/dfu.c
+++ b/cmd/dfu.c
@@ -30,7 +30,7 @@
 #if defined(CONFIG_DFU_OVER_USB) || defined(CONFIG_DFU_OVER_TFTP)
 	char *interface = NULL;
 	char *devstring = NULL;
-#if defined(CONFIG_DFU_OVER_TFTP)
+#if defined(CONFIG_DFU_TIMEOUT) || defined(CONFIG_DFU_OVER_TFTP)
 	unsigned long value = 0;
 #endif
 
@@ -39,7 +39,7 @@
 		devstring = argv[3];
 	}
 
-#if defined(CONFIG_DFU_OVER_TFTP)
+#if defined(CONFIG_DFU_TIMEOUT) || defined(CONFIG_DFU_OVER_TFTP)
 	if (argc == 5 || argc == 3)
 		value = simple_strtoul(argv[argc - 1], NULL, 0);
 #endif
@@ -55,6 +55,10 @@
 	if (ret)
 		goto done;
 
+#ifdef CONFIG_DFU_TIMEOUT
+	dfu_set_timeout(value * 1000);
+#endif
+
 	ret = CMD_RET_SUCCESS;
 	if (strcmp(argv[argc - 1], "list") == 0) {
 		dfu_show_entities();
@@ -75,10 +79,17 @@
 	"Device Firmware Upgrade",
 	""
 #ifdef CONFIG_DFU_OVER_USB
+#ifdef CONFIG_DFU_TIMEOUT
+	"<USB_controller> [<interface> <dev>] [<timeout>] [list]\n"
+#else
 	"<USB_controller> [<interface> <dev>] [list]\n"
+#endif
 	"  - device firmware upgrade via <USB_controller>\n"
 	"    on device <dev>, attached to interface\n"
 	"    <interface>\n"
+#ifdef CONFIG_DFU_TIMEOUT
+	"    [<timeout>] - specify inactivity timeout in seconds\n"
+#endif
 	"    [list] - list available alt settings\n"
 #endif
 #ifdef CONFIG_DFU_OVER_TFTP