base: fix freeing the time and data_array
base: fix freeing the time and data_array

if a is an array a[:] creates a copy of the array, so assigning to it
should not have any effect.  Just assign an empty array to time_array
and data_array and let the garbage collector take care of the previous
references.

Change-Id: I693361a3856730af90240a0465ccbd5c2d1d8acd

derkling/trappy,JaviMerino/trappy,derkling/trappy,derkling/trappy,sinkap/trappy,JaviMerino/trappy,sinkap/trappy,bjackman/trappy,bjackman/trappy,ARM-software/trappy,joelagnel/trappy,ARM-software/trappy,joelagnel/trappy,joelagnel/trappy,joelagnel/trappy,sinkap/trappy,ARM-software/trappy,bjackman/trappy,ARM-software/trappy,JaviMerino/trappy,sinkap/trappy,bjackman/trappy