Return the result from user admin command IOCTL even in case of failure

We copy the result to user if the command is completed from the
controller even if it completes with failure (non-zero) status.
A return status of < 0 indicates the command was not completed
by the controller. The user application may expect the error code
in the result field in case of failure.

Signed-off-by: Chayan Biswas <Chayan.Biswas@sandisk.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>