qemu: Remove useless table from qemuArchBase

The supportedQemuMachines array in qemuArchBase has a list of all the
qemu machine types supported for the architecture, with the options
for each.  But, the machineType field already tells us which of the
machine types we're actually using, and that's the only entry we
actually care about.

So, drop the table, and just have a single value with the machine type
we're actually using.  As a bonus that means the machine() method can
no longer fail, so no longer needs an error return.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

src/runtime/virtcontainers/qemu_test.go

@@ -342,7 +342,10 @@ func TestQemuQemuPath(t *testing.T) {
 	qemuConfig := newQemuConfig()
 	qemuConfig.HypervisorPath = expectedPath
 	qkvm := &qemuArchBase{
-		machineType: "pc",
+		qemuMachine: govmmQemu.Machine{
+			Type: "pc",
+			Options: "",
+		},
 		qemuPaths: map[string]string{
 			"pc": expectedPath,
 		},
@@ -371,7 +374,7 @@ func TestQemuQemuPath(t *testing.T) {
 	assert.Equal(path, expectedPath)
 
 	// bad machine type, arch should fail
-	qkvm.machineType = "rgb"
+	qkvm.qemuMachine.Type = "rgb"
 	q.arch = qkvm
 	path, err = q.qemuPath()
 	assert.Error(err)