Update stm32l476rg linker scripts for bootloader

Add MBED_APP_START and MBED_APP_SIZE to the linker scripts
so the start and size of an image can be specified. This allows the
ROM to be split into a bootloader region and an application region.

Author: LMESTM

targets/TARGET_STM/TARGET_STM32L4/TARGET_STM32L476xG/device/TOOLCHAIN_ARM_MICRO/stm32l476xx.sct

@@ -1,3 +1,4 @@
+#! armcc -E
 ; Scatter-Loading Description File
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; Copyright (c) 2015, STMicroelectronics
@@ -27,10 +28,18 @@
 ; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+#if !defined(MBED_APP_START)
+  #define MBED_APP_START 0x08000000
+#endif
+
+#if !defined(MBED_APP_SIZE)
+  #define MBED_APP_SIZE 0x200000
+#endif
+
 ; 1MB FLASH (0x100000) + 128KB SRAM (0x20000)
-LR_IROM1 0x08000000 0x100000  {    ; load region size_region
+LR_IROM1 MBED_APP_START MBED_APP_SIZE  {    ; load region size_region
 
-  ER_IROM1 0x08000000 0x100000  {  ; load address = execution address
+  ER_IROM1 MBED_APP_START MBED_APP_SIZE  {  ; load address = execution address
    *.o (RESET, +First)
    *(InRoot$$Sections)
    .ANY (+RO)

targets/TARGET_STM/TARGET_STM32L4/TARGET_STM32L476xG/device/TOOLCHAIN_ARM_STD/stm32l476xx.sct

@@ -1,3 +1,4 @@
+#! armcc -E
 ; Scatter-Loading Description File
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; Copyright (c) 2015, STMicroelectronics
@@ -27,10 +28,18 @@
 ; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+#if !defined(MBED_APP_START)
+  #define MBED_APP_START 0x08000000
+#endif
+
+#if !defined(MBED_APP_SIZE)
+  #define MBED_APP_SIZE 0x200000
+#endif
+
 ; 1MB FLASH (0x100000) + 128KB SRAM (0x20000)
-LR_IROM1 0x08000000 0x100000  {    ; load region size_region
+LR_IROM1 MBED_APP_START MBED_APP_SIZE  {    ; load region size_region
 
-  ER_IROM1 0x08000000 0x100000  {  ; load address = execution address
+  ER_IROM1 MBED_APP_START MBED_APP_SIZE  {  ; load address = execution address
    *.o (RESET, +First)
    *(InRoot$$Sections)
    .ANY (+RO)

targets/TARGET_STM/TARGET_STM32L4/TARGET_STM32L476xG/device/TOOLCHAIN_GCC_ARM/STM32L476XX.ld

@@ -1,7 +1,16 @@
+#if !defined(MBED_APP_START)
+  #define MBED_APP_START 0x08000000
+#endif
+
+#if !defined(MBED_APP_SIZE)
+  #define MBED_APP_SIZE 2048k
+#endif
+
 /* Linker script to configure memory regions. */
 MEMORY
 { 
-  FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 1024K
+  VECTORS (rx) : ORIGIN = MBED_APP_START, LENGTH = 0x400
+  FLASH (rx)   : ORIGIN = MBED_APP_START + 0x400, LENGTH = MBED_APP_SIZE - 0x400
   SRAM2 (rwx)  : ORIGIN = 0x10000188, LENGTH = 32k - 0x188
   SRAM1 (rwx)  : ORIGIN = 0x20000000, LENGTH = 96k
 }

targets/TARGET_STM/TARGET_STM32L4/TARGET_STM32L476xG/device/TOOLCHAIN_IAR/stm32l476xx.icf

@@ -1,7 +1,10 @@
+if (!isdefinedsymbol(MBED_APP_START)) { define symbol MBED_APP_START = 0x08000000; }
+if (!isdefinedsymbol(MBED_APP_SIZE)) { define symbol MBED_APP_SIZE = 0x200000; }
+
 /* [ROM = 1024kb = 0x100000] */
-define symbol __intvec_start__     = 0x08000000;
-define symbol __region_ROM_start__ = 0x08000000;
-define symbol __region_ROM_end__   = 0x080FFFFF;
+define symbol __intvec_start__     = MBED_APP_START;
+define symbol __region_ROM_start__ = MBED_APP_START;
+define symbol __region_ROM_end__   = MBED_APP_START + MBED_APP_SIZE - 1;
 
 /* [RAM = 96kb + 32kb = 0x20000] */
 /* Vector table dynamic copy: Total: 98 vectors = 392 bytes (0x188) to be reserved in RAM */