MFC r256753

MFP4: 1136252

Add an option ATSE_CFI_HACK to allow memory mapped CFI devices to have
their address range allocated sharable so that atse(4) can find it's
Ethernet address in the expected location.

We intend to remove this hack once the BERI platform has a loader.

Sponsored by: DARPA/AFRL
Approved by: re (gjb)