dracut: fix host-user-contaminated

Fixed:
dracut-043+giteab03540cd695d940062af5b55c02e8829aaa526: dracut: /dracut/usr/lib/dracut/modules.d/99img-lib/img-lib.sh is owned by uid 15220, which is the same as the user running bitbake. This may be due to host contamination [host-user-contaminated]
lib32-dracut-043+giteab03540cd695d940062af5b55c02e8829aaa526: lib32-dracut: /lib32-dracut/usr/lib/dracut/modules.d/99img-lib/img-lib.sh is owned by uid 15220, which is the same as the user running bitbake. This may be due to host contamination [host-user-contaminated]

Its Makefile uses cp -arx to install modules.d, so fix the owner
to root:root

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>