This adds Gateworks Laguna family board support.  Note that some Laguna
boards have SPI flash and others have NOR flash, thus the size/erasesize
are detected dynamically.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

git-svn-id: svn://svn.openwrt.org/openwrt@36313 3c298f89-4303-0410-b956-a3cf2f4a3e73