linux-wandboard (3.0.35): add recipe for 'official' wandboard kernel

Adds a recipe to build a kernel using the 'offical' wandboard
git repository.  Recipe is two parts.  linux-wandboard.inc specifies
items that should not change very often (e.g. SRCURI).  The .bb
file specifies the SRCREV and other things that could change
quite often.
wandboard-dual: Make linux-wandboard preferred provider

With the addition of the linux-wandboard recipes, which build the
Wandboard kernel from the 'official' kernel source for Wandboard, change
the PREFERRED_PROVIDER to 'linux-wandboard'.
linux-imx (3.0.35): Remove wandboard from recipe

With the addition of the linux-wandboard recipe, we remove wandboard
support from the linux-imx recipes in order to prevent confusion and keep
all Wandboard effort focused on the 'official' Wandboard kernel.