qemu_cgroup: Avoid ternary operator when setting @deviceACL

qemu_cgroup: Avoid ternary operator when setting @deviceACL

Inside of the qemuSetupDevicesCgroup() there's @deviceACL
variable, which points to a string list of devices that are
allowed in devices controller by default. This list can either
come from qemu.conf (cfg->cgroupDeviceACL) or from a builtin
@defaultDeviceACL. However, a multiline ternary operator is used
when setting the variable which is against our coding style.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>