staging: slicoss: use status in slic_ioctl

In the ioctl function if we are not able to UP the link after setting
the new parameters then return an error code to the userspace.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>