scsi: qla1280: properly handle 64-bit DMA

CONFIG_HIGHMEM is not in fact an indicator for > 32-bit dma addressing
Given that the driver is a bit weird and wants a compile time selection
switch to checking CONFIG_ARCH_DMA_ADDR_T_64BIT instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla1280.c

@@ -383,10 +383,7 @@
 
 #include "qla1280.h"
 
-#ifndef BITS_PER_LONG
-#error "BITS_PER_LONG not defined!"
-#endif
-#if (BITS_PER_LONG == 64) || defined CONFIG_HIGHMEM
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
 #define QLA_64BIT_PTR	1
 #endif