recipes-phoshor: fans: add phosphor-pid-control

Initial phosphor-pid-control recipe.  This installs the swampd daemon.
It is expected that each platform will provide their own start-up
service at present because of current dependencies on dbus.

Change-Id: I5ea4b31a99580b42f33488878cc1ec97dd94e582
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/meta-phosphor/classes/phosphor-pid-control.bbclass b/meta-phosphor/classes/phosphor-pid-control.bbclass
new file mode 100644
index 0000000..573420b
--- /dev/null
+++ b/meta-phosphor/classes/phosphor-pid-control.bbclass
@@ -0,0 +1,2 @@
+sensor_datadir="${datadir}/swampd/sensor"
+