IMX DSP is only needed by SOF or any other module that
wants to communicate with the DSP. When SOF is build
as a module IMX DSP is forced to be built inside the
kernel image. This is not optimal, so allow IMX DSP
to be built as a module.
Signed-off-by: NDaniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>