[SCSI] megaraid_sas: Set 32-bit DMA mask

If consistent DMA mask is set to 64 bit, fall back to 32bit DMA mask and 32bit consistent DMA mask.
64bit consistent DMA mask may be set on some 64bit DMA slot, which causes DMA offset "10000000000000" and
MFI_INIT and IOCTL frames will have high memory addresses, leads to firmware FAULT.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: Sumit Saxena <sumit.saxena@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>