Move selection of linker script in meson.build

Now the linker script was moved from cross_arm.txt into meson.build, so
that the same cross_arm.txt can be used for both the MD380 and the GD77.

cross_arm.txt

@@ -28,7 +28,6 @@ c_link_args = [
                '-Wl,--gc-sections',
                '-Wl,-Map,main.map',
                '-nostdlib',
-               '-Wl,-T../platform/mcu/STM32F4xx/linker_script.ld',
                '-Wl,--start-group',
                '-lc',
                '-lgcc',

meson.build

@@ -188,11 +188,13 @@ linux_opts = {'sources': linux_src,
 
 md380_opts = {'sources': md380_src,
               'c_args': md380_args,
+              'link_args' : '-Wl,-T../platform/mcu/STM32F4xx/linker_script.ld',
               'include_directories': md380_inc}
 
 
 mduv380_opts = {'sources': mduv380_src,
                 'c_args': mduv380_args,
+                'link_args' : '-Wl,-T../platform/mcu/STM32F4xx/linker_script.ld',
                 'include_directories': mduv380_inc}
 
 ##