ath10k: Add support for htt_data_tx_desc_64 descriptor

WCN3990 target uses 64 bit frags_paddr in htt tx descriptor,
which holds the physical address of SKB fragments in tx data path.

In order to support 64 bit bit frags_paddr in htt tx descriptor, define
htt_data_tx_desc_64 descriptor and ath10k_htt_tx_64 method for handling
tx data path with new descriptor fields.

Signed-off-by: Govind Singh <govinds@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>