[SCSI] mptsas : PAE Kernel more than 4 GB kernel panic

This patch is solving problem for PAE kernel DMA operation.
On PAE system dma_addr and unsigned long will have different
values.
Now dma_addr is not type casted using unsigned long.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>