led: Remove unused plugin

This was originally developed for a custom device.  No known users for
years.

conf/Makefile.am

@@ -70,7 +70,6 @@ plugins = \
 	plugins/imv-swima.opt \
 	plugins/imv-test.opt \
 	plugins/ipseckey.opt \
-	plugins/led.opt \
 	plugins/kernel-libipsec.opt \
 	plugins/kernel-netlink.opt \
 	plugins/kernel-pfkey.opt \

conf/plugins/led.opt

@@ -1,3 +0,0 @@
-charon.plugins.led.activity_led =
-
-charon.plugins.led.blink_time = 50