The router Nucom R5010UN v2 has the partitions defined for a 8MB flash,
but the flash chip is 16MB size. We are wasting half of the flash.
Fix it and use generic names for partitions.
Fixes: 474cde6123 ("brcm63xx: probe SPI flash through DT")
Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>