scsi: cxlflash: Support starting an adapter context

Once the adapter context is created, it needs to be started by assigning the
MMIO space for the context and by enabling the process element in the
link. This commit adds the skeleton for starting the context and assigns the
context specific MMIO space. Master contexts have access to the global MMIO
space while the rest have access to the context specific space.

Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>