drivers: staging : wlan-ng : collect return status without variable

As caller rdev_set_default_key  not particular about -EFAULT.
We can preserve the return value of prism2_domibset_uint32.

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
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Changes in v2:
  - remove  masking of original return value with EFAULT
Changes in v3:
  - merge patch v1 and v2 sothat it can be applied on linux-next
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>