As of commit 2a00ef6e which
was released in v5.2.0, we require YAJL to build the QEMU driver.

Remove the checks from code that requires the QEMU driver
or checks that also check for WITH_QEMU.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>