Vendor attributes to retain connection on a roam request failure

Vendor attributes to retain connection on a roam request failure

This commit introduces the following two attributes to
QCA_NL80211_VENDOR_SUBCMD_KEY_MGMT_ROAM_AUTH events:

QCA_WLAN_VENDOR_ATTR_ROAM_AUTH_STATUS - Indicates the status of
	re-association requested by user space
QCA_WLAN_VENDOR_ATTR_ROAM_AUTH_RETAIN_CONNECTION - Indicates whether
	the old association was maintained when a re-association
	is requested by user space and that re-association attempt
	fails (i.e., cannot connect to the requested BSS, but can
	remain associated with the BSS with which the association was
	in place when being requested to roam).

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>