[SCSI] dpt_i2o: 64 bit support

This is the code to actually support 64 bit platforms. 64 bit
DMA is enabled on both x86_32 PAE and 64 bit platforms.

This code is based in part on the unofficial adaptec 64-bit
dpt_i2o driver update that I got from Mark Salyzyn at Adaptec.

Signed-off-by: Miquel van Smoorenburg <miquels@cistron.nl>
Acked-by: Mark Salyzyn <Mark_Salyzyn@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>