ath10k: add QCA9887 chipset support

Add the hardware name, revision, firmware names and update the pci_id
table.

QA9887 HW1.0 is supposed to be similar to QCA988X HW2.0 . Details about
he firmware interface are currently unknown.

Signed-off-by: Sven Eckelmann <sven.eckelmann@open-mesh.com>
[kvalo@qca.qualcomm.com: add a warning about experimental support]
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>