Add schema definition for PCI configuration feature including:
- Add <pci> element under <features>
- Add <highmem-mmio-size> element with scaledInteger type
- Support unit attribute for size specification

This allows XML configuration of PCI high memory MMIO size
for aarch64 virt machines.

Signed-off-by: Matthew R. Ochs <mochs@nvidia.com>
---
 src/conf/schemas/domaincommon.rng | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
index 96cedb85e867..7f3ac7b8295f 100644
--- a/src/conf/schemas/domaincommon.rng
+++ b/src/conf/schemas/domaincommon.rng
@@ -6999,6 +6999,15 @@
           <optional>
             <ref name="aia"/>
           </optional>
+          <optional>
+            <element name='pci'>
+              <optional>
+                <element name='highmem-mmio-size'>
+                  <ref name='scaledInteger'/>
+                </element>
+              </optional>
+            </element>
+          </optional>
         </interleave>
       </element>
     </optional>
-- 
2.46.0