iommu/vt-d: Do not use GFP_ATOMIC when not needed

There is no need to use GFP_ATOMIC here. GFP_KERNEL is already used for
some other memory allocations just a few lines above.

Commit e3a981d6 ("iommu/vt-d: Convert allocations to GFP_KERNEL") has
changed the other memory allocation flags.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/e2a8a1019ffc8a86b4b4ed93def3623f60581274.1675542576.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>