common: Convert the U-Boot commands to LG-arrays

This patch converts the old method of creating a list of command
onto the new LG-arrays code. The old u_boot_cmd section is converted
to new u_boot_list_cmd subsection and LG-array macros used as needed.

Minor adjustments had to be made to the common code to work with the
LG-array macros, mostly the fixup_cmdtable() calls are now passed the
ll_entry_start and ll_entry_count instead of linker-generated symbols.

The command.c had to be adjusted as well so it would use the newly
introduced LG-array API instead of directly using linker-generated
symbols.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
diff --git a/doc/README.commands b/doc/README.commands
index 125f077..923418b 100644
--- a/doc/README.commands
+++ b/doc/README.commands
@@ -15,12 +15,12 @@
 
 **** Behind the scene ******
 
-The structure created is named with a special prefix (__u_boot_cmd_)
+The structure created is named with a special prefix (__u_boot_list_cmd_)
 and placed by the linker in a special section.
 
 This makes it possible for the final link to extract all commands
 compiled into any object code and construct a static array so the
-command can be found in an array starting at __u_boot_cmd_start.
+command can be found in an array starting at _u_boot_list_cmd__start.
 
 To ensure that the linker does not discard these symbols when linking
 full U-Boot we generate a list of all the commands we have built (based
@@ -33,6 +33,6 @@
 by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these
 3 lines:
 
-	__u_boot_cmd_start = .;
-	.u_boot_cmd : { *(.u_boot_cmd) }
-	__u_boot_cmd_end = .;
+	.u_boot_list : {
+	#include "u-boot.lst";
+	}