ARM: 8909/1: make unexported items static

Fixup the following sparse warnings by making the functions and structures
static.

arch/arm/mm/dma-mapping.c:1562:6: warning: symbol '__arm_iommu_free_attrs' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1586:6: warning: symbol 'arm_iommu_free_attrs' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1592:6: warning: symbol 'arm_coherent_iommu_free_attrs' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1716:5: warning: symbol 'arm_coherent_iommu_map_sg' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1734:5: warning: symbol 'arm_iommu_map_sg' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1767:6: warning: symbol 'arm_coherent_iommu_unmap_sg' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1784:6: warning: symbol 'arm_iommu_unmap_sg' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1798:6: warning: symbol 'arm_iommu_sync_sg_for_cpu' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:1816:6: warning: symbol 'arm_iommu_sync_sg_for_device' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:2018:26: warning: symbol 'iommu_ops' was not declared. Should it be static?
arch/arm/mm/dma-mapping.c:2040:26: warning: symbol 'iommu_coherent_ops' was not declared. Should it be static?

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>