wifi: ti: Avoid a hundred -Wflex-array-member-not-at-end warnings

-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

Remove unused flexible-array members in multiple structures, and fix
a hundred -Wflex-array-member-not-at-end warnings[1] in
drivers/wireless/ti/

Link: https://gist.github.com/GustavoARSilva/fbf63c114d01319bbd19baf95b4d704b [1]
Link: https://github.com/KSPP/linux/issues/202


Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/ZgDcwIgxkhs6ZVdY@neat