iova: Stop exporting some more functions

The following functions are not referenced outside dma-iommu.c (and
iova.c), which can only be built-in:
- init_iova_flush_queue()
- free_iova_fast()
- queue_iova()
- alloc_iova_fast()

So stop exporting them.

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/1609940111-28563-4-git-send-email-john.garry@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iova.c

@@ -112,7 +112,6 @@ int init_iova_flush_queue(struct iova_domain *iovad,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(init_iova_flush_queue);
 
 static struct rb_node *
 __get_cached_rbnode(struct iova_domain *iovad, unsigned long limit_pfn)
@@ -451,7 +450,6 @@ retry:
 
 	return new_iova->pfn_lo;
 }
-EXPORT_SYMBOL_GPL(alloc_iova_fast);
 
 /**
  * free_iova_fast - free iova pfn range into rcache
@@ -598,7 +596,6 @@ void queue_iova(struct iova_domain *iovad,
 		mod_timer(&iovad->fq_timer,
 			  jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
 }
-EXPORT_SYMBOL_GPL(queue_iova);
 
 /**
  * put_iova_domain - destroys the iova domain