qemu.tests: Add a case migration with an ide disk doing pio operation

This case will do following steps:
  - disable dma in guest kernel command line to make sure ide disk using pio
  - check the pio and dma status inside guest
  - run iozone in background
  - do tcp migration

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
Merge pull request #119 from ypu/migrate_with_pio

qemu.tests: Add a case migration with an ide disk doing pio operation