SEV: Update ReducedPhysBits

Updating this field, as `cpuid` provides host level data, which is not
what a guest would expect for Reduced Phsycial Bits. In almost all
cases, we should be using `1` for the value here.

Amend: Adding unit test change.

Fixes: #5006

Signed-off-by: Larry Dewey <larry.dewey@amd.com>
(cherry picked from commit 67b8f0773f)

src/runtime/virtcontainers/qemu_amd64.go

@@ -261,7 +261,7 @@ func (q *qemuAmd64) appendProtectionDevice(devices []govmmQemu.Device, firmware,
 				Debug:           false,
 				File:            firmware,
 				CBitPos:         cpuid.AMDMemEncrypt.CBitPosition,
-				ReducedPhysBits: cpuid.AMDMemEncrypt.PhysAddrReduction,
+				ReducedPhysBits: 1,
 			}), "", nil
 	case noneProtection:
 		return devices, firmware, nil

src/runtime/virtcontainers/qemu_amd64_test.go

@@ -287,7 +287,7 @@ func TestQemuAmd64AppendProtectionDevice(t *testing.T) {
 			Debug:           false,
 			File:            firmware,
 			CBitPos:         cpuid.AMDMemEncrypt.CBitPosition,
-			ReducedPhysBits: cpuid.AMDMemEncrypt.PhysAddrReduction,
+			ReducedPhysBits: 1,
 		},
 	}