include/configs/[g-o]*: Cleanup BOOTP and lingering CFG_CMD_*.

Explicitly add in default CONFIG_BOOTP_* options where cmd_confdefs.h
used to be included but CONFIG_BOOTP_MASK was not defined.

Remove lingering references to CFG_CMD_* symbols.

Signed-off-by: Jon Loeliger <jdl@freescale.com>