linux-wrs: Add support for atom-pc

linux-wrs: Add support for atom-pc

Add the option of using linux-wrs as the kernel provider for atom-pc. This
patch uses poky to apply config fragments to the common_pc-standard branch
of the linux-wrs kernel. A follow-on patch will remove these once linux-wrs
has an atom-pc branch and the config fragments are present in the kernel
repository.

This configuration boots to a prompt on the BlackSand, but panics unable
to find the root partition on the Toshiba NB305 where the "rootwait"
kernel boot option appears to be being ignored.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>