staging: ks7010: Remove unecessary cast.

The driver casts '&ks_wlan_handler_def' to 'struct iw_handler_def *',
but it is already of that type.

Signed-off-by: Quytelda Kahja <quytelda@tamalin.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>