ath11k: qmi: avoid error messages when dma allocation fails

qmi tries to allocate a large contiguous dma memory at first,
on the AMD Ryzen platform it fails, then retries with small slices.
So set flag GFP_NOWARN to avoid flooding dmesg.

Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210823063258.37747-1-aaron.ma@canonical.com