dt: bindings: add new DT entry for ath11k PCI device support

Ath11k driver supports PCI devices such as QCN9074/QCA6390.
Ath11k firmware uses host DDR memory, DT entry is used to
reserve host DDR memory regions, send these memory base
addresses using DT entries.

Signed-off-by: Anilkumar Kolli <akolli@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/1638789319-2950-1-git-send-email-akolli@codeaurora.org