logger: Add an enable toggle for entry storage; TNX AndreiLux and Dorimanx

You can disable logging by echo-ing 0 in /sys/module/logger/parameters/log_enabled
By default the logging is enabled.

Change-Id: I2d4c8d61f58c002454f6fc4b10a107e0ef389efa

Conflicts:
	drivers/staging/android/logger.c