OvmfPkg/QemuBootOrderLib: clean up translation of virtio-net over MMIO

The "/MAC(" suffix of the translated UEFI devpath prefix is unnecessary
for matching, because the virtio-mmio base address in VenHwString is
unique anyway. Furthermore, the partial string "MAC(" cannot be processed
by ConvertTextToDevicePath(), which will become relevant later in this
series. Remove "/MAC(".

While at it, remove a bogus comment on PCI.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Shannon Zhao <zhaoshenglong@huawei.com>
Cc: Xiang Zheng <xiang.zheng@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> # ArmVirtQemu
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Xiang Zheng <xiang.zheng@linaro.org>

OvmfPkg/Library/QemuBootOrderLib/QemuBootOrderLib.c

@@ -1217,14 +1217,14 @@ TranslateMmioOfwNodes (
     //                |                             fixed
     //                base address of virtio-mmio register block
     //
-    // UEFI device path prefix (dependent on presence of nonzero PCI function):
+    // UEFI device path prefix:
     //
-    //   <VenHwString>/MAC(
+    //   <VenHwString>
     //
     Written = UnicodeSPrintAsciiFormat (
                 Translated,
                 *TranslatedSize * sizeof (*Translated), // BufferSize in bytes
-                "%s/MAC(",
+                "%s",
                 VenHwString
                 );
   } else {