Turns out it doesn't behave as expected on MacOS, it doesn't honor
-n and echoes that to the file instead. Add a slash and just let
the newline be there instead.
Signed-off-by: Olof Johansson <olof@lixom.net>
Some toolchains might not have all the CSRs available (as seen with
GCC 7.2). So, instead use the defined CSR_ values.
Signed-off-by: Olof Johansson <olof@lixom.net>