Added test_expand_mbr_image test case to the wic oe-selftest suite.
The test expands directdisk wic image to 1Gb target, checks if it's
expanded correctly and boots it in qemu to make sure the image
is bootable, i.e. bootloader, kernel, boot and root partitions
are still functional.
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
