cmd: map addresses to sysmem in efidebug memmap

Addresses in the sandbox's device tree are in the sandbox's virtual address
space. If we want to compare memory reservations in the device-tree with
the output of 'efidebug memmap', we need to convert back to this address
space.

Adjust the output of the 'efidebug memmap' command.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>