ath10k: update tx path to support QCA99X0

Since QCA99X0 uses fragmentation descriptor differently from
other ones on tx path, we need to handle it separately.

QCA99X0 is using 48 bits for address and 16 bits for length
out of 2 dword and each values have to be programmed by frag
desc base addr + msdu id, so that hardware can retrieve
corresponding frag data.

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