cmd/ti: Update Kconfig logic and Makefile recursion logic

- Add some dependencies to CMD_DDR3 as this is only valid on some
  platforms (which tend to select it as well).
- The proper gate for going in to cmd/ti is not
  CONFIG_TI_COMMON_CMD_OPTIONS as nothing under there is controlled by
  that symbol but the general TI architecture options.

Signed-off-by: Tom Rini <trini@konsulko.com>