wifi: mwifiex: fix loop iterator in mwifiex_update_ampdu_txwinsize()

This code re-uses "i" to be the iterator for both the inside and outside
loops.  It means the outside loop will exit earlier than intended.

Fixes: d219b7eb ("mwifiex: handle BT coex event to adjust Rx BA window size")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/Y+ERnaDaZD7RtLvX@kili