qemu.tests: Add check SGABIOS info case for seabios.py

This patch add the restart vm function.

Changes from v2:
update some parameter name.

Signed-off-by: Shuping Cui <scui@redhat.com>
Signed-off-by: Yiqiao Pu <ypu@redhat.com>
Acked-by: Feng Yang <fyang@redhat.com>