Adding service file

Service file for swampd has been added

Signed-off-by: Vijay Khemka <vijaykhemka@fb.com>
Change-Id: If449c0e943f1a82e9d18599391f0dc68c28009ec
diff --git a/Makefile.am b/Makefile.am
index 3283236..45b26d4 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -38,6 +38,10 @@
 AM_CFLAGS = $(CODE_COVERAGE_CFLAGS)
 AM_CXXFLAGS = $(CODE_COVERAGE_CXXFLAGS)
 
+if HAVE_SYSTEMD
+systemdsystemunit_DATA = phosphor-pid-control.service
+endif
+
 bin_PROGRAMS = swampd setsensor
 
 setsensor_SOURCES = setsensor.cpp