After supporting dual kernels(std, rt) in one image,
there is no need to set separated work directories
for std and rt types.
Test Plan:
Pass: 'build-image --std' works and
the '/localdisk/' is the build directory
Pass: 'build-image --rt' works and
the '/localdisk/' is the build directory
Story: 2008846
Task: 45725
Signed-off-by: Haiqing Bai <haiqing.bai@windriver.com>
Change-Id: If690ce9a426337c3f5657d52bfbd119cb8f6d384
095e59c907