cmd: Update the meminfo command to show the memory map

U-Boot has a fairly rigid memory map which is normally not visible
unless debugging is enabled in board_f.c

Update the 'meminfo' command to show it. This command does not cover
arch-specific pieces but gives a good overview of where things are.

Signed-off-by: Simon Glass <sjg@chromium.org>

cmd/Kconfig

@@ -889,6 +889,17 @@ config CMD_MEMINFO
 	help
 	  Display memory information.
 
+config CMD_MEMINFO_MAP
+	bool "- with memory map"
+	depends on CMD_MEMINFO
+	default y if SANDBOX
+	help
+	  Shows a memory map, in addition to just the DRAM size. This allows
+	  seeing where U-Boot's memory area is, at the top of DRAM, as well as
+	  detail about each piece of it.
+
+	  See doc/usage/cmd/meminfo.rst for more information.
+
 config CMD_MEMORY
 	bool "md, mm, nm, mw, cp, cmp, base, loop"
 	default y