phosphor-sel-logger: add clears-sel PACKAGECONFIG option

This option will enable phosphor-sel-logger to clear the SEL log
files.

Signed-off-by: Charles Boyer <Charles.Boyer@fii-usa.com>
Change-Id: Ia710a2f1a901b18c78f8d54109761589cf5d5c2b
diff --git a/meta-phosphor/recipes-phosphor/sel-logger/phosphor-sel-logger_git.bb b/meta-phosphor/recipes-phosphor/sel-logger/phosphor-sel-logger_git.bb
index e4c8f68..ac4f270 100644
--- a/meta-phosphor/recipes-phosphor/sel-logger/phosphor-sel-logger_git.bb
+++ b/meta-phosphor/recipes-phosphor/sel-logger/phosphor-sel-logger_git.bb
@@ -34,3 +34,4 @@
 PACKAGECONFIG[log-watchdog] = "-Dlog-watchdog=true,-Dlog-watchdog=false,"
 PACKAGECONFIG[log-alarm] = "-Dlog-alarm=true,-Dlog-alarm=false,"
 PACKAGECONFIG[send-to-logger] = "-Dsend-to-logger=true,-Dsend-to-logger=false,phosphor-logging"
+PACKAGECONFIG[clears-sel] = "-Dclears-sel=true,-Dclears-sel=false"