Change HCODE image build to use ATTR instead of scom

  Remove HW dependancy in p9_hcode_image_build and use
  ATTR instead

Change-Id: I97e9641af2e2f73e5691a975ed885496f89b941e
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/31593
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Prachi Gupta <pragupta@us.ibm.com>
Reviewed-by: Prem Shanker Jha <premjha2@in.ibm.com>
Reviewed-by: Gregory S. Still <stillgs@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/41216
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>

src/import/chips/p9/procedures/xml/attribute_info/p9_hcode_image_build_attributes.xml

@@ -37,4 +37,16 @@
   <enum> CORE_UNFUSED = 0x0, CORE_FUSED = 0x1 </enum>
   <platInit/>
 </attribute>
+
+<attribute>
+  <id>ATTR_HOMER_PHYS_ADDR</id>
+  <targetType>TARGET_TYPE_PROC_CHIP</targetType>
+  <description>
+    Physical real address of the HOMER image for this chip.  Used to
+    tell the CME where this HOMER image will be placed. Must be
+    aligned to a 4MB boundary
+  </description>
+  <valueType>uint64</valueType>
+  <platInit/>
+</attribute>
 </attributes>