arm: kirkwood: pogo_v4: Add Distro boot capability

arm: kirkwood: pogo_v4: Add Distro boot capability

- Add distro boot to board include file and deconfig file
- Miscellaneous changes:
	- Add CONFIG_SUPPORT_PASSING_ATAGS and friends to support legacy
	kernel method of booting (e.g. OpenWrt) with appended DTB.
	- Add CONFIG_LTO and CONFIG_UBIFS_SILENCE_MSG, and disable some
	unused configs	to reduce binary size.

Note that this patch is depended on the following patch:
https://patchwork.ozlabs.org/project/uboot/patch/20220807192709.21717-1-pali@kernel.org/

Signed-off-by: Tony Dinh <mibodhi@gmail.com>