board: starqltechn: get board usable - add bootcmd and docs

board: starqltechn: get board usable - add bootcmd and docs

U-boot is intended to replace linux kernel in android boot image(ABL), and
it's FIT payload to replace initramfs file. The boot process is similar to
boot image with linux:
- android bootloader (ABL) unpacks android boot image
- ABL sets `linux,initrd-start property` in chosen node in unpacked FDT
- ABL sets x0 register to FDT address, and passes control to u-boot
- u-boot reads x0 register, and stores it in `prevbl_fdt_addr` env variable
- u-boot reads `linux,initrd-start` property,
and stores it in `prevbl_initrd_start_addr`

In this way, u-boot bootcmd relies on `prevbl_initrd_start_addr` env
variable, and boils down to `bootm $prevbl_initrd_start_addr`.
If more control on boot process is desired, pack a boot script in
FIT image, and put it to default configuration

What done:
- strip unneeded config options
- add FIT image support
- add framebuffer node, u-boot logo and video console
- increase LMB_MAX_REGIONS, to store all linux dtb reserved memory regions
- add linux kernel image header

Uart driver causes hang, when u-boot is used in android boot image instead
of linux. Temporary disable console driver, until investigated and fixed.

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Cc: Ramon Fried <rfried.dev@gmail.com>