doc: marvell: Update build manual with new memory layouts

Add description for memory layouts used by EspressoBin v7 (DDR4)

Change-Id: I199d8b52580b26e560f14b503a6e99d32de4f284
Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/61279


Reviewed-by: Stefan Chulski <stefanc@marvell.com>
Tested-by: iSoC Platform CI <ykjenk@marvell.com>