build: Remove unused presence variable

Change-Id: I72f801067ff09c91c53d32bf5ebb66fed3ec4dfc
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/configure.ac b/configure.ac
index 1c45658..1e6afd0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -74,18 +74,12 @@
 # Package specific checks.
 AS_IF([test "x$enable_presence" != "xno"], [
        # Add optional yaml file argument
-       AC_ARG_VAR(FAN_DETECT_YAML_FILE,
-                  [The fan presence detection definition file to use])
        AC_ARG_VAR(PRESENCE_CONFIG,
                   [The fan presence config file.])
 
-       AS_IF([test "x$FAN_DETECT_YAML_FILE" == "x"],
-             [FAN_DETECT_YAML_FILE="\${top_srcdir}/presence/example/fan-detect.yaml"])
        AS_IF([test "x$PRESENCE_CONFIG" == "x"],
              [PRESENCE_CONFIG="\${top_srcdir}/presence/example/example.yaml"])
 
-       AC_DEFINE_UNQUOTED([FAN_DETECT_YAML_FILE], ["$FAN_DETECT_YAML_FILE"],
-                          [The fan presence detection definition file to use])
        AC_DEFINE_UNQUOTED([PRESENCE_CONFIG], ["$PRESENCE_CONFIG"],
                           [The fan presence config file.])