scsi: aacraid: pci_alloc_consistent() failures on ARM64

There were pci_alloc_consistent() failures on ARM64 platform.  Use
dma_alloc_coherent() with GFP_KERNEL flag DMA memory allocations.

Signed-off-by: Mahesh Rajashekhara <mahesh.rajashekhara@microsemi.com>
[hch: tweaked indentation, removed memsets]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Dave Carroll <david.carroll@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>