staging: ks7010: remove not used definition WPA_CAPABILITY_PREAUTH

The WPA_CAPABILITY_PREAUTH definition is not being used at all so
just remove it.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>