ath11k: set correct NL80211_FEATURE_DYNAMIC_SMPS for WCN6855

Commit 6f4d7030 ("ath11k: support SMPS configuration for 6 GHz") changed
"if (ht_cap & WMI_HT_CAP_DYNAMIC_SMPS)" to "if (ht_cap &
WMI_HT_CAP_DYNAMIC_SMPS || ar->supports_6ghz)" which means
NL80211_FEATURE_DYNAMIC_SMPS is enabled for all chips which support 6 GHz.
However, WCN6855 supports 6 GHz but it does not support feature
NL80211_FEATURE_DYNAMIC_SMPS, and this can lead to MU-MIMO test failures for
WCN6855.

Disable NL80211_FEATURE_DYNAMIC_SMPS for WCN6855 since its ht_cap does not
support WMI_HT_CAP_DYNAMIC_SMPS. Enable the feature only on QCN9074 as that's
the only other device supporting 6 GHz band.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1

Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210914163726.38604-3-jouni@codeaurora.org