iommu/dart: Clean up IOVA cookie crumbs

The addition of the DART driver crossed over with moving IOVA cookie
management into core code; clean up the now-unnecessary remnants here.
Acked-by: Sven Peter <sven@svenpeter.dev>
Tested-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/edb72b4965baa8999dd70b8294785d6deebd4183.1631531973.git.robin.murphy@arm.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/apple-dart.c

@@ -15,7 +15,6 @@
 #include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/dev_printk.h>
-#include <linux/dma-iommu.h>
 #include <linux/dma-mapping.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
@@ -596,7 +595,6 @@ static struct iommu_domain *apple_dart_domain_alloc(unsigned int type)
 	if (!dart_domain)
 		return NULL;
 
-	iommu_get_dma_cookie(&dart_domain->domain);
 	mutex_init(&dart_domain->init_lock);
 
 	/* no need to allocate pgtbl_ops or do any other finalization steps */