When using QCA6174 PCI devices working in station mode, after connected
to AP, tx bitrate is always '1.0 MBit/s' in output of command 'iw wlan0
station dump'. (QCA6174 SDIO devices are working fine.)

After this patch, it show correct bitrate:

Station c4:04:15:5d:97:22 (on wls1)
        inactive time:  312 ms
        rx bytes:       31496
        rx packets:     173
        tx bytes:       8625
        tx packets:     46
        tx retries:     0
        tx failed:      0
        signal:         -76 [-88, -80] dBm
        signal avg:     -75 [-82, -77] dBm
        tx bitrate:     39.0 MBit/s MCS 4
        rx bitrate:     26.0 MBit/s MCS 3

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1597312029-32348-4-git-send-email-wgong@codeaurora.org