libertas: Fix WEP association failure with open source wpa_supplicant 0.5.10

Add code to handle IW_AUTH_PRIVACY_INVOKED and IW_AUTH_RX_UNENCRYPTED_EAPOL
cases in lbs_set_auth() function in libertas code.

Signed-off-by: Maithili Hinge <maithili@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>