DMA buffer descriptors aren't allocated from atomic context, so they
can use the less heavyweigth GFP_NOWAIT.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de> Signed-off-by: Robin Gong <yibin.gong@nxp.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Vinod Koul <vkoul@kernel.org>