tools: kwbimage: Add support for dumping NAND_BLKSZ for v0 images

tools: kwbimage: Add support for dumping NAND_BLKSZ for v0 images

In Dove functional specification, which use kwbimage v0, is also defined
nand block size field. So dump NAND_BLKSZ also for v0 images.

In Kirkwood functional specification, which also use kwbimage v0, this
field is not defined. So when it is zero and Kirkwood is detected, do not
dump it.

Fixes: 873ac5d34cda ("tools: kwbimage: Add support for dumping extended and binary v0 headers")
Signed-off-by: Pali Rohár <pali@kernel.org>