staging: ks7010: refactor ks_wlan_set_wps_enable function

This commit refactors ks_wlan_set_wps_enable function to
improve readability handling the error first to avoid an
'else'.

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