There's one more thing that wants dynpart computed block offset -
the kernel offset used for NAND boot.
This patch moves the business end of the dynparts computation into
the port_init_gta02() so it's done earlier, and writes the block
index into the board_api struct NAND option's partition block start
field.
It also adds a field to the nand_dynparts struct so we can hold both
the true length and true block offset for each partition for later
use by the original code in append_device_specific_cmdline_gta02.
Signed-off-by: Andy Green <andy@openmoko.com>