linux-yocto_{3.14,3.19,4.1}: qemuarm enable virtio drivers

linux-yocto_{3.14,3.19,4.1}: qemuarm enable virtio drivers

We are experimenting segfault in qemu arm SCSI driver because
it's broken [1][2] so enable virtio drivers to use as default.

[YOCTO #8060]

[1] https://lists.gnu.org/archive/html/qemu-devel/2007-03/msg00093.html
[2] https://lists.nongnu.org/archive/html/qemu-devel/2010-07/msg01473.html

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>