kvm: use -machine type,accel= for newer qemu
kvm: use -machine type,accel= for newer qemu

-enable-kvm and -disable-kvm are deprecated in favor of accel=kvm passed
as a machine specification. This fixes compatibility with newer qemu
versions.

Signed-off-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

yiannist/ganeti,ganeti/ganeti,leshchevds/ganeti,bitemyapp/ganeti,andir/ganeti,leshchevds/ganeti,andir/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,grnet/snf-ganeti,mbakke/ganeti,leshchevds/ganeti,dimara/ganeti,apyrgio/ganeti,andir/ganeti,grnet/snf-ganeti,dimara/ganeti,yiannist/ganeti,ganeti/ganeti,yiannist/ganeti,apyrgio/ganeti,mbakke/ganeti,mbakke/ganeti,onponomarev/ganeti,bitemyapp/ganeti,apyrgio/snf-ganeti,ganeti-github-testing/ganeti-test-1,ganeti-github-testing/ganeti-test-1,ganeti/ganeti