[SCSI] fnic: On system with >1.1TB RAM, VIC fails multipath after boot up

Issue was seen when SCSI buffer address is more than 40 bits in system
with more than 1.1TB RAM. When SCSI buffer is passed to VIC, it is failing
to map to correct buffer address, as DMA mask is set to 40 bits in driver
initialization. Corrected DMA_MASK from 40-bits to 64-bits to avoid masking
41-64 bits addresses.

Signed-off-by: Brian Uchino <buchino@cisco.com>
Signed-off-by: Hiral Patel <hiralpat@cisco.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>