mips: octeon: tools: Add update_octeon_header tool

mips: octeon: tools: Add update_octeon_header tool

Add a tool to update or insert an Octeon specific header into the U-Boot
image. This is needed e.g. for booting via SPI NOR, eMMC and NAND.

While working on this, move enum cvmx_board_types_enum and
cvmx_board_type_to_string() to cvmx-bootloader.h and remove the
unreferenced (unsupported) board definition.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>