iommu: Change api header to static inline

Update the function header of iommu_fwspec_get_id to static inline
so compilation proceeds when CONFIG_IOMMU_API=n.

Change-Id: Ib903e537cf26d1352a7c13c843269ebcd369a128
Signed-off-by: Runmin Wang <runminw@codeaurora.org>
1 file changed