wifi: mac80211: fold tid_ampdu_rx allocations into a flexible array

wifi: mac80211: fold tid_ampdu_rx allocations into a flexible array

Convert the separately-allocated reorder_buf pointer to a C99 flexible
array member at the end of struct tid_ampdu_rx, with both the
sk_buff_head and the jiffies timestamp in each array element. This
collapses three allocations into one and removes the corresponding
kfree() pairs from the error and free paths.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://patch.msgid.link/20260605005627.317194-1-rosenp@gmail.com
[fix kernel-doc]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>