staging: mei: fix typo in error code return

~ENODEV is a different number than -ENODEV

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>