[*] Rootfs+Initramfs: Add support for various behaviour of uart terminal and telnetd depending on setted envoronment.

Add support the next build variables:
ROOTFS_DISABLE_CONSOLE_SHELL - disables starting login or shell on uart.
ROOTFS_DISABLE_AUTO_LOGIN - start login before enter into shell on uart.
ROOTFS_DISABLE_TELNETD - disable starting telnet server.

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>
[*] Buildroot: Always call fb_logo makefile for building.

If necessary we should check dependences inside fb_logo makefile.

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>