wifi: ath11k: fix rx completion meta data corruption

wifi: ath11k: fix rx completion meta data corruption

Add the missing memory barrier to make sure that the REO dest ring
descriptor is read after the head pointer to avoid using stale data on
weakly ordered architectures like aarch64.

This may fix the ring-buffer corruption worked around by commit
f9fff67d2d7c ("wifi: ath11k: Fix SKB corruption in REO destination
ring") by silently discarding data, and may possibly also address user
reported errors like:

	ath11k_pci 0006:01:00.0: msdu_done bit in attention is not set

Tested-on: WCN6855 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Cc: stable@vger.kernel.org	# 5.6
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218005
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Clayton Craft <clayton@craftyguy.net>
Link: https://patch.msgid.link/20250321145302.4775-1-johan+linaro@kernel.org
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>