tests: Update test cases use vm_arch_name instead of platform

platform is an old parameter we used. Should use vm_arch_name now.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
qemu.tests: Use parameter vm_arch_name to judge guest os arch

image_name may be customized and not end with 64.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
qemu.tests: Calculate fill timeout based on the ksm size

As the ksm size is calculate based on guest and host memory status,
when we run tests in big host, we need fill very big size of memory.
With current set up, it will failed with timeout to wait the results.

Signed-off-by: Yiqiao Pu <ypu@redhat.com>
Merge pull request #1129 from ypu/ksm

Enlarge ksm overcommit test time