Perf: Make per-process counters cumulative
In order to get overall value for performance counters, remove reset during context switches. Add mechanism to calculate deltas for output to the trace buffer. Change-Id: I03d894a1b3bd400d8c256c3068f917ed001fbfd9 Signed-off-by: Sheetal Sahasrabudhe <sheetals@codeaurora.org>

Signed-off-by: evolutionmod <kernelcraft@gmail.com>