misc: ibmvsm: Fix wrong assignment of return code

Currently the assignment is flipped and rc is always 0.

Signed-off-by: Bryant G. Ly <bryantly@linux.ibm.com>
Fixes: 0eca353e ("misc: IBM Virtual Management Channel Driver (VMC)")
Reviewed-by: Bradley Warrum <bwarrum@us.ibm.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>