bsps: Fix input data type on irq-generic.c/.h

- Constify bsp_interrupt_entry_find()

- bsp_interrupt_entry_find does not modify
the object referenced by arg, it only compares
pointer values against it.

- changed the parameter type from void* to
const void* in both declaration and
definition to make it correct and safer.

Update #4816

bsps/include/bsp/irq-generic.h

@@ -703,7 +703,7 @@ rtems_status_code bsp_interrupt_check_and_lock(
 rtems_interrupt_entry *bsp_interrupt_entry_find(
   rtems_vector_number      vector,
   rtems_interrupt_handler  routine,
-  void                    *arg,
+  const void              *arg,
   rtems_interrupt_entry ***previous_next
 );
 

bsps/shared/irq/irq-generic.c

@@ -136,7 +136,7 @@ rtems_status_code bsp_interrupt_check_and_lock(
 rtems_interrupt_entry *bsp_interrupt_entry_find(
   rtems_vector_number      vector,
   rtems_interrupt_handler  routine,
-  void                    *arg,
+  const void              *arg,
   rtems_interrupt_entry ***previous_next
 )
 {