swiotlb: Remove redundant __GFP_NOWARN

Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
made GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT
(e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean
up these redundant flags across subsystems.

No functional changes.

Signed-off-by: Qianfeng Rong <[e-mail]>
Signed-off-by: Marek Szyprowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

kernel/dma/swiotlb.c

···
 	nslabs = nr_slots(alloc_size);
 	phys_limit = min_not_zero(*dev->dma_mask, dev->bus_dma_limit);
 	pool = swiotlb_alloc_pool(dev, nslabs, nslabs, 1, phys_limit,
-				  GFP_NOWAIT | __GFP_NOWARN);
+				  GFP_NOWAIT);
 	if (!pool)
 		return -1;