staging: wilc1000: fix mgmt_tx()

There was a missing curly brace so this function returns failure instead
of succeeding.

Fixes: 06fb9336 ('staging: wilc1000: wilc_wfi_cfgoperations.c: replaces PRINT_ER with netdev_err')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>