Fix typo in comment (FreeRTOS#398)

Author: andresovela

tasks.c

@@ -2140,7 +2140,7 @@ void vTaskSuspendAll( void )
      * post in the FreeRTOS support forum before reporting this as a bug! -
      * https://goo.gl/wu4acr */
 
-    /* portSOFRWARE_BARRIER() is only implemented for emulated/simulated ports that
+    /* portSOFTWARE_BARRIER() is only implemented for emulated/simulated ports that
      * do not otherwise exhibit real time behaviour. */
     portSOFTWARE_BARRIER();