staging/slicoss: return -ENODEV if no devid matches

if no case matches we are simply asserting and doing break.
and i think we may need to return that -ENODEV , no device is
present, rather assert'ing.

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>