The bootz and booti commands rely on common functionality that is found
in common/bootm.c and common/bootm_os.c. They do not however rely on
the rest of cmd/bootm.c to be implemented so split them into their own
files. Have various Makefiles include the required infrastructure for
CONFIG_CMD_BOOT[IZ] as well as CONFIG_CMD_BOOTM. Move the declaration
of 'images' over to common/bootm.c.
Cc: Masahiro Yamada <email@example.com>
Signed-off-by: Tom Rini <firstname.lastname@example.org>