ath10k: enable QCA6174 hw3.2 SDIO hardware

After implementing PN replay check we can enable SDIO support on QCA6174.
Tested with client mode on all security modes, and fragmentation as well. AP
mode does not work yet.

Also tone down the warning about SDIO being not ready yet.

Tested on QCA6174 SDIO with firmware WLAN.RMH.4.4.1-00007-QCARMSWP-1. AP mode
is not working yet.

Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>