ath10k: add support for qca99x0 Rx descriptors

QCA99X0 chip has an extra 4 bytes in rx_msdu_start,
20 bytes in rx_msdu_end and 20 bytes in rx_ppdu_end structure
which are used in htt_rx_desc and HTT Rx ring offset setup.
This is necessary for correct Rx for QCA99X0 or Rx descriptors
will be overwritten and corrupted.

With this patch QCA988X and QCA6174 will have extra 44 bytes
padding in Rx descriptor layout which is harmless.

Signed-off-by: Peter Oh <poh@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>