staging: ks7010: refactor ks_wlan_set_pmksa function

This commit cleans a bit ks_wlan_set_pmksa function removing
nonsense comments as well as make use of ether_addr_* family
functions written to not do manually things that were being
here. Minor single if brackets has been removed also.

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