sdcard_image-sunxi.bbclass: fixing race condition with virtual/kernel (resolves #15)

Fixing a race condition with virtual/kernel:do_deploy,
which needs to deploy the image before the IMAGE_CMD_sunxi-sdimg () code is being run
as part of image:do_rootfs, otherwise the following error would sometimes occur
when compiling with multiple threads (BB_NUMBER_THREADS=2):
"[..]/deploy/images/cubieboard2/uImage-cubieboard2.bin: No such file or directory"

Fixing this by using the kernel image in sysrootfs instead.

At the same time, also adding an explicit rootfs dependency on sunxi-board-fex:do_deploy because of
"${DEPLOY_DIR_IMAGE}/fex.bin", although this never seems to pose problems in practice.
Merge pull request #16 from KristofRobot/sdcard_race_cond2

sdcard_image-sunxi.bbclass: fixing race condition with virtual/kernel (r...
Merge pull request #18 from chenbd/master

Add support for cubietruck
linux_3.4.bb: fix QA warnings/errors (resolves #14)
set the right uboot-machine
Merge pull request #21 from vonfritz/upstream-master

set the right uboot-machine
Merge pull request #20 from KristofRobot/issue14

linux_3.4.bb: fix QA warnings/errors (resolves #14)