Update the FD mapping so the volatile areas write back to the FD file. Currently...

Update the FD mapping so the volatile areas write back to the FD file. Currently they are only mapped as a  memory copy of the file. This also make FV read only.

The current scheme maps a file into a memory buffer. You can write to the memory buffer, but if you restart the emulator the data is not written back to the FD. Since the build, rebuilds the FD it will blow away any changes. You can now set variables and restart the emulator and they are still set. There is a bug if the FV is set to write protect that still needs to be tracked down.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11761 6f19259b-4bc3-4df7-8a09-765794883524