x86: efi: Show the system-table revision

Show the revision of this table as it can be important.

Also update the 'efi table' entry to show the actual address of the EFI
table rather than our table that points to it. This saves a step and the
intermediate table has nothing else in it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>