wait_ns micro-optimisation

Use `+ 1` to set the "Thumb" indicator on the `delay_loop` routine
address, rather than `| 1`. That makes it something that can be done
by the linker, rather than needing to be done at run-time.

Saves one instruction and one cycle.

platform/mbed_wait_api_no_rtos.c

@@ -142,7 +142,7 @@ static const uint16_t delay_loop_code[] = {
 };
 
 /* Take the address of the code, set LSB to indicate Thumb, and cast to void() function pointer */
-#define delay_loop ((void(*)()) ((uintptr_t) delay_loop_code | 1))
+#define delay_loop ((void(*)()) ((uintptr_t) delay_loop_code + 1))
 
 /* Some targets may not provide zero-wait-state flash performance. Export this function
  * to be overridable for targets to provide more accurate implementation like locating