Rather than sticking Blackfin-specific stuff into the eeprom example, use
an indirect macro so that any board can override it with their own magic
sauce in their board config file.

Also fix some spurious semi-colons in defines while I'm at it ...

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
CC: Ben Warren <biggerbadderben@gmail.com>