sdio bus bandwidth is low, sometimes for high performance TX test,
it will lack of ath10k_sdio_bus_request, it will print message:
ath10k_sdio mmc1:0001:1: unable to allocate bus request for async request

change the num from 64 to 1024 will not happen it.

Tested with QCA6174 SDIO with firmware
WLAN.RMH.4.4.1-00017-QCARMSWP-1.
Signed-off-by: Wen Gong <wgong@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200212080415.31265-3-wgong@codeaurora.org