set NRF52832 static_memory_defines true

static_memory_defines controls the macro MBED_RAM_START AND MBED_RAM_SIZE
when nrf52832 to use softdevice, it need MBED_RAM_START to set the true application ram start

Author: woodsking2

targets/targets.json

@@ -7332,7 +7332,7 @@
     "MCU_NRF52832": {
         "inherits": ["Target"],
         "core": "Cortex-M4F",
-        "static_memory_defines": false,
+        "static_memory_defines": true,
         "macros": [
             "BOARD_PCA10040",
             "NRF52",