[IA64] SN specific version of dma_get_required_mask()

Create a platform specific version of dma_get_required_mask()
for ia64 SN Altix. All SN Altix platforms support 64 bit DMA
addressing regardless of the size of system memory.
Create an ia64 machvec for dma_get_required_mask, with the
SN version unconditionally returning DMA_64BIT_MASK.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/include/asm/machvec_sn2.h b/arch/ia64/include/asm/machvec_sn2.h
index 781308e..f1a6e0d 100644
--- a/arch/ia64/include/asm/machvec_sn2.h
+++ b/arch/ia64/include/asm/machvec_sn2.h
@@ -67,6 +67,7 @@
 extern ia64_mv_dma_sync_sg_for_device	sn_dma_sync_sg_for_device;
 extern ia64_mv_dma_mapping_error	sn_dma_mapping_error;
 extern ia64_mv_dma_supported		sn_dma_supported;
+extern ia64_mv_dma_get_required_mask	sn_dma_get_required_mask;
 extern ia64_mv_migrate_t		sn_migrate;
 extern ia64_mv_kernel_launch_event_t	sn_kernel_launch_event;
 extern ia64_mv_setup_msi_irq_t		sn_setup_msi_irq;
@@ -123,6 +124,7 @@
 #define platform_dma_sync_sg_for_device	sn_dma_sync_sg_for_device
 #define platform_dma_mapping_error		sn_dma_mapping_error
 #define platform_dma_supported		sn_dma_supported
+#define platform_dma_get_required_mask	sn_dma_get_required_mask
 #define platform_migrate		sn_migrate
 #define platform_kernel_launch_event    sn_kernel_launch_event
 #ifdef CONFIG_PCI_MSI