utils.py: Add function for processing profile output

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
build.py: Dump out performance data of individual tasks

Signed-off-by: Richard  Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>