meta-phosphor: pid-control: use json instead of libconfig

The requirement for libconfig has been removed.  Add new dependency on
json.

Change-Id: Ic1a9e9540816a49a2bd72fd4d429c58876e48b85
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/recipes-phosphor/fans/phosphor-pid-control_git.bb b/recipes-phosphor/fans/phosphor-pid-control_git.bb
index 30a6a06..599ee76 100644
--- a/recipes-phosphor/fans/phosphor-pid-control_git.bb
+++ b/recipes-phosphor/fans/phosphor-pid-control_git.bb
@@ -27,7 +27,7 @@
 DEPENDS += "sdbusplus"
 DEPENDS += "phosphor-logging"
 DEPENDS += "libevdev"
-DEPENDS += "libconfig"
+DEPENDS += "nlohmann-json"
 
 # We depend on someone providing their system's configuration.
 DEPENDS += "virtual/phosphor-fans-sensor-inventory"