wifi: ath12k: fix warning when unbinding

wifi: ath12k: fix warning when unbinding

commit ca68ce0d9f4bcd032fd1334441175ae399642a06 upstream.

If there is an error during some initialization related to firmware,
the buffers dp->tx_ring[i].tx_status are released.
However this is released again when the device is unbinded (ath12k_pci),
and we get:
WARNING: CPU: 0 PID: 2098 at mm/slub.c:4689 free_large_kmalloc+0x4d/0x80
Call Trace:
free_large_kmalloc
ath12k_dp_free
ath12k_core_deinit
ath12k_pci_remove
...

The issue is always reproducible from a VM because the MSI addressing
initialization is failing.

In order to fix the issue, just set the buffers to NULL after releasing in
order to avoid the double free.

cc: stable@vger.kernel.org
Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
Link: https://patch.msgid.link/20241017181004.199589-3-jtornosm@redhat.com
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>