iommu/iova: Fix compilation error with !CONFIG_IOMMU_IOVA

The stub function for !CONFIG_IOMMU_IOVA needs to be
'static inline'.

Fixes: effa4678 ('iommu/vt-d: Don't queue_iova() if there is no flush queue')
Signed-off-by: Joerg Roedel <jroedel@suse.de>

include/linux/iova.h

@@ -236,7 +236,7 @@ static inline void init_iova_domain(struct iova_domain *iovad,
 {
 }
 
-bool has_iova_flush_queue(struct iova_domain *iovad)
+static inline bool has_iova_flush_queue(struct iova_domain *iovad)
 {
 	return false;
 }