Add effectiveFamily, effectiveModel and Step to AMD Zen family

Reference:
https://kib.kiev.ua/x86docs/AMD/AMD-CPUID-Spec/25481-r2.28.pdf

Change-Id: Ic4df2ab047a561e565ea3c72321d3e0dc42067e4
Signed-off-by: Konda Reddy Kachana <kkachana@google.com>
diff --git a/src/cpu.cpp b/src/cpu.cpp
index 3a586a2..93566e9 100644
--- a/src/cpu.cpp
+++ b/src/cpu.cpp
@@ -183,7 +183,8 @@
     {
         std::string familyStr = it->second;
         if ((familyStr.find(" Xeon ") != std::string::npos) ||
-            (familyStr.find(" Intel ") != std::string::npos))
+            (familyStr.find(" Intel ") != std::string::npos) ||
+            (familyStr.find(" Zen ") != std::string::npos))
         {
             // Processor ID field
             // SteppinID:   4;