libvirt: Fix wrong depend for libxl
libvirt: Fix wrong depend for libxl

xen is not the right dependency for --with-libxl/--without-libxl, replace
it to libxl.

Signed-off-by: Yang Shi <13279bcd383f6312e7c872835c77108bbfc630d5@windriver.com>
Signed-off-by: Bruce Ashfield <284cc737d174a260eec2a2a6324a304f84b1ae0f@windriver.com>

cardoe/meta-virtualization,fbertux/meta-virtualization,cjp256/meta-virtualization,cardoe/meta-virtualization,errordeveloper/oe-meta-virtualization,cjp256/meta-virtualization,lgirdk/meta-virtualization,cardoe/meta-virtualization,lgirdk/meta-virtualization,lgirdk/meta-virtualization,lgirdk/meta-virtualization,fbertux/meta-virtualization,cjp256/meta-virtualization,lgirdk/meta-virtualization,rcwoolley/meta-virtualization,fbertux/meta-virtualization