Get CPU port dynamically in fabric interpreter

Different HW platforms have different CPU ports, here we allow using
the same interpreter with multiple platform.

Change-Id: I0895d4d3e11560c75aca3fa908ca38759b597d67
diff --git a/pipelines/fabric/src/main/resources/bmv2-compile.sh b/pipelines/fabric/src/main/resources/bmv2-compile.sh
index d92a5c4..b0ac43e 100755
--- a/pipelines/fabric/src/main/resources/bmv2-compile.sh
+++ b/pipelines/fabric/src/main/resources/bmv2-compile.sh
@@ -18,3 +18,5 @@
         --p4runtime-file ${OUT_DIR}/p4info.txt \
         --p4runtime-format text \
         fabric.p4
+
+echo ${BMV2_CPU_PORT} > ${OUT_DIR}/cpu_port.txt