metricsd: Remove unused constant.

Change-Id: Id151c4a7a091ee9cb07fa7c6188d162cf342d70e
diff --git a/metricsd/metrics_daemon.cc b/metricsd/metrics_daemon.cc
index cf4d79d..2838119 100644
--- a/metricsd/metrics_daemon.cc
+++ b/metricsd/metrics_daemon.cc
@@ -84,8 +84,6 @@
 const int kMetricStatsShortInterval = 1;  // seconds
 const int kMetricStatsLongInterval = 30;  // seconds
 
-const int kMetricMeminfoInterval = 30;        // seconds
-
 // Assume a max rate of 250Mb/s for reads (worse for writes) and 512 byte
 // sectors.
 const int kMetricSectorsIOMax = 500000;  // sectors/second