QCA6390 does not support monitor mode at the moment so disable it altogether,
using a hack as mac80211 does not support disabling it otherwise. Add a boolean
to hw_params to know if hardware supports monitor mode.

IPQ8074 continues to support monitor mode normally.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1601399736-3210-6-git-send-email-kvalo@codeaurora.org