After the conversion to the new Memory API, vga_dirty_log_restart became
seriously pointless. Remove it from vmware-vga and and then finally drop
the service.

CC: Andrzej Zaborowski <balrogg@gmail.com>
CC: Avi Kivity <avi@redhat.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>