Remove inherit of qemuboot classes when not build for qemu in
xen-image-minimal.
When reverted the handling for only adding inherited classes for qemu
was kept but the line always inheriting them was kept to.
This patch is fixing that so that qemuboot classes are now only added
when the image is built for qemu.
This fixes commit 27e5ade0ab
Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
3e6c50b794