ath10k: fix kernel panic, move arvifs list head init before htt init

ath10k: fix kernel panic, move arvifs list head init before htt init

It is observed that while loading and unloading ath10k modules
in an infinite loop, before ath10k_core_start() completion HTT
rx frames are received, while processing these frames,
dereferencing the arvifs list code is getting hit before
initilizing the arvifs list, causing a kernel panic.

This patch initilizes the arvifs list before initilizing htt.

Fixes the below issue:
 [<bf88b058>] (ath10k_htt_rx_pktlog_completion_handler+0x278/0xd08 [ath10k_core])
 [<bf88b058>] (ath10k_htt_rx_pktlog_completion_handler [ath10k_core])
 [<bf88c0dc>] (ath10k_htt_txrx_compl_task+0x5f4/0xeb0 [ath10k_core])
 [<bf88c0dc>] (ath10k_htt_txrx_compl_task [ath10k_core])
 [<c0234100>] (tasklet_action+0x8c/0xec)
 [<c0234100>] (tasklet_action)
 [<c02337c0>] (__do_softirq+0xf8/0x228)
 [<c02337c0>] (__do_softirq)  [<c0233920>] (run_ksoftirqd+0x30/0x90)
 Code: e5954ad8 e2899008 e1540009 0a00000d (e5943008)
 ---[ end trace 71de5c2e011dbf56 ]---
 Kernel panic - not syncing: Fatal exception in interrupt

Fixes: 500ff9f9389d ("ath10k: implement chanctx API")
Cc: <stable@vger.kernel.org>
Signed-off-by: Anilkumar Kolli <akolli@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>