Fix dev_print when called from usb_stor_info (usb storage command)

Fix output of the usb storage command. It was printing "Device 0: not
available" because IF_TYPE_USB was not included into the switch
statement.

Signed-off-by: Nicolas Lebedenco <nicolas.lebedenco@tasksistemas.com.br>

disk/part.c

@@ -124,6 +124,12 @@ void dev_print (block_dev_desc_t *dev_desc)
 			dev_desc->revision,
 			dev_desc->product);
 		break;
+	case IF_TYPE_USB:
+		printf ("Vendor: %s Rev: %s Prod: %s\n",
+			dev_desc->vendor,
+			dev_desc->revision,
+			dev_desc->product);
+		break;
 	case IF_TYPE_UNKNOWN:
 	default:
 		puts ("not available\n");