[bsp][stm32] update stm32h743-st-nucleo/board/SConscript to fix compiling error after dist

bsp/stm32/stm32h743-st-nucleo/board/SConscript

 import rtconfig
 from building import *
 
+Import('SDK_LIB')
+
 cwd = GetCurrentDir()
 
 # add the general drivers.
@@ -10,12 +12,14 @@ src += Glob('CubeMX_Config/Src/stm32h7xx_hal_msp.c')
 path = [cwd]
 path += [cwd + '/CubeMX_Config/Inc']
 
+startup_path_prefix = SDK_LIB
+
 if rtconfig.CROSS_TOOL == 'gcc':
-    src += [cwd + '/../../libraries/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/gcc/startup_stm32h743xx.s']
+    src += [startup_path_prefix + '/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/gcc/startup_stm32h743xx.s']
 elif rtconfig.CROSS_TOOL == 'keil':
-    src += [cwd + '/../../libraries/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/arm/startup_stm32h743xx.s']
+    src += [startup_path_prefix + '/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/arm/startup_stm32h743xx.s']
 elif rtconfig.CROSS_TOOL == 'iar':
-    src += [cwd + '/../../libraries/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/iar/startup_stm32h743xx.s']
+    src += [startup_path_prefix + '/STM32H7xx_HAL/CMSIS/Device/ST/STM32H7xx/Source/Templates/iar/startup_stm32h743xx.s']
 
 # STM32H743xx || STM32H750xx || STM32F753xx
 # You can select chips from the list above