wifi: wilc1000: fix RCU usage in connect path

With lockdep enabled, calls to the connect function from cfg802.11 layer
lead to the following warning:

=============================
WARNING: suspicious RCU usage
6.7.0-rc1-wt+ #333 Not tainted
-----------------------------
drivers/net/wireless/microchip/wilc1000/hif.c:386
suspicious rcu_dereference_check() usage!
[...]
stack backtrace:
CPU: 0 PID: 100 Comm: wpa_supplicant Not tainted 6.7.0-rc1-wt+ #333
Hardware name: Atmel SAMA5
 unwind_backtrace from show_stack+0x18/0x1c
 show_stack from dump_stack_lvl+0x34/0x48
 dump_stack_lvl from wilc_parse_join_bss_param+0x7dc/0x7f4
 wilc_parse_join_bss_param from connect+0x2c4/0x648
 connect from cfg80211_connect+0x30c/0xb74
 cfg80211_connect from nl80211_connect+0x860/0xa94
 nl80211_connect from genl_rcv_msg+0x3fc/0x59c
 genl_rcv_msg from netlink_rcv_skb+0xd0/0x1f8
 netlink_rcv_skb from genl_rcv+0x2c/0x3c
 genl_rcv from netlink_unicast+0x3b0/0x550
 netlink_unicast from netlink_sendmsg+0x368/0x688
 netlink_sendmsg from ____sys_sendmsg+0x190/0x430
 ____sys_sendmsg from ___sys_sendmsg+0x110/0x158
 ___sys_sendmsg from sys_sendmsg+0xe8/0x150
 sys_sendmsg from ret_fast_syscall+0x0/0x1c

This warning is emitted because in the connect path, when trying to parse
target BSS parameters, we dereference a RCU pointer whithout being in RCU
critical section.
Fix RCU dereference usage by moving it to a RCU read critical section. To
avoid wrapping the whole wilc_parse_join_bss_param under the critical
section, just use the critical section to copy ies data

Fixes: c460495e

 ("staging: wilc1000: fix incorrent type in initializer")
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240105075733.36331-3-alexis.lothore@bootlin.com