dma_get_required_mask for ARM64

[Suravee Suthikulanit]

Hi Catalin/Will,

In the arch/arm64/include/asm/dma-mapping.h defines the macro 
"ARCH_HAS_DMA_GET_REQUIRED_MASK".  However, I can't seem to find where 
the function "dma_get_required_mask" defined for ARM64. I got a 
compilation error when building one of the driver:

ERROR: "dma_get_required_mask" [drivers/scsi/mpt2sas/mpt2sas.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2

Is this function defined anywhere for ARM64?

Thank you,

Suravee