nl80211: Add NL80211_ATTR_MLO_LINK_ID for NL80211_CMD_REMAIN_ON_CHANNEL

nl80211: Add NL80211_ATTR_MLO_LINK_ID for NL80211_CMD_REMAIN_ON_CHANNEL

cfg80211 requires the link ID to be specified for requests to start a
remain-on-channel operation during an ML association. This feels wrong
since the ROC operation is in most cases unrelated to the
association. However, that requirement has been in place since kernel
commit 7b0a0e3c3a88 ("wifi: cfg80211: do some rework towards MLO link
APIs") from April 2022, and as such, it looks necessary to have
wpa_supplicant work around this by specifying the currently used link ID
that would seem to match the ROC channel most closely.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>