Fix MISRA_C_2012 rule 17.7 violation (#848)

* Assign return value of xPortStartScheduler API to a variable

* Add void datatype

---------

Co-authored-by: chinglee-iot <61685396+chinglee-iot@users.noreply.github.com>
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>

tasks.c

@@ -3727,7 +3727,10 @@ void vTaskStartScheduler( void )
 
         /* Setting up the timer tick is hardware specific and thus in the
          * portable interface. */
-        xPortStartScheduler();
+
+        /* The return value for xPortStartScheduler is not required
+         * hence using a void datatype. */
+        ( void ) xPortStartScheduler();
 
         /* In most cases, xPortStartScheduler() will not return. If it
          * returns pdTRUE then there was not enough heap memory available