fix zram intialization if zram is build into kernel

Sometimes ZRAM is built into the kernel itself. In this case the number of available ZRAM devices doesn't always have to match with the number of CPUs. This APP should take care of this case:

	zramstart(){
	...
	local devices=`ls /dev/block/zram*`;
	local ndevices=0;
	
	for j in $devices; do
		ndevices=$(( ndevices + 1 ));
	done
	...
	}