[BMP upload] Fix compiler path

Fixes #986

Signed-off-by: Frederic Pillon <[email protected]>

Author: fpistm

platform.txt

@@ -171,7 +171,7 @@ tools.stm32CubeProg.upload.pattern="{path}/{cmd}" {upload.protocol} "{build.path
 
 # blackmagic upload for generic STM32
 tools.bmp_upload.cmd=arm-none-eabi-gdb
-tools.bmp_upload.path={runtime.tools.arm-none-eabi-gcc.path}/bin/
+tools.bmp_upload.path={compiler.path}
 tools.bmp_upload.upload.speed=230400
 tools.bmp_upload.upload.params.verbose=-batch
 tools.bmp_upload.upload.params.quiet=--batch-silent