LSM303D: start handler fix and start routine review

src/drivers/lsm303d/lsm303d.cpp

@@ -1803,6 +1803,9 @@ void	usage();
 
 /**
  * Start the driver.
+ *
+ * This function call only returns once the driver is
+ * up and running or failed to detect the sensor.
  */
 void
 start(bool external_bus, enum Rotation rotation)

src/drivers/lsm303d/module.mk

@@ -5,4 +5,4 @@
 MODULE_COMMAND	 = lsm303d
 SRCS		 = lsm303d.cpp
 
-
+MODULE_STACKSIZE	= 1200