u-boot: Add yocto u-boot plus patches.

Provide u-boot_v2013.01.01 with Xilinx specific patches for xilinx-v2013.01
Required small changes to common include files so they can be shared
between u-boot and u-boot-xlnx.

Signed-off-by: Sipke Vriend <sipke.vriend@xilinx.com>