Remove ifdef guard around uvisor_ctx macro

mbed OS has been updated and we no longer need to provide the backwards
compatibility `ifdef` guard. Remove the `ifdef` guard as unnecessary.

Author: Patater

source/led1.cpp

@@ -22,11 +22,7 @@ UVISOR_BOX_HEAPSIZE(3 * 1024);
 UVISOR_BOX_MAIN(led1_main, osPriorityNormal, 512);
 UVISOR_BOX_CONFIG(box_led1, acl, 512, box_context);
 
-/* FIXME: The guard is needed for backwards-compatibility reasons. Remove it
- *        when mbed OS is updated. */
-#ifdef __uvisor_ctx
 #define uvisor_ctx ((box_context *) __uvisor_ctx)
-#endif
 
 static void led1_main(const void *)
 {

source/led2.cpp

@@ -22,11 +22,7 @@ UVISOR_BOX_HEAPSIZE(3 * 1024);
 UVISOR_BOX_MAIN(led2_main, osPriorityNormal, 512);
 UVISOR_BOX_CONFIG(box_led2, acl, 512, box_context);
 
-/* FIXME: The guard is needed for backwards-compatibility reasons. Remove it
- *        when mbed OS is updated. */
-#ifdef __uvisor_ctx
 #define uvisor_ctx ((box_context *) __uvisor_ctx)
-#endif
 
 static void led2_main(const void *)
 {

source/led3.cpp

@@ -22,11 +22,7 @@ UVISOR_BOX_HEAPSIZE(3 * 1024);
 UVISOR_BOX_MAIN(led3_main, osPriorityNormal, 1024);
 UVISOR_BOX_CONFIG(box_led3, acl, 512, box_context);
 
-/* FIXME: The guard is needed for backwards-compatibility reasons. Remove it
- *        when mbed OS is updated. */
-#ifdef __uvisor_ctx
 #define uvisor_ctx ((box_context *) __uvisor_ctx)
-#endif
 
 static void run_3(void)
 {