staging: vt6656: fix potential leak in vt6656_hostap_ioctl()

Commit fb841d67 (staging: vt6656: don't leak 'param' in vt6656_hostap_ioctl()
when returning -EOPNOTSUPP) cleaned up direct returns in the ioctl switch
statement that leaked already allocated memory. Fix the same issue for
VIAWGET_HOSTAPD_SCAN_REQ and VIAWGET_HOSTAPD_MLME that are not supported by
this driver. Detected by Coverity - CID 144381.

Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>