proc: show present cpu instead of online cpu in /proc/stat

Some userspace applications use /proc/stat to determine how many CPUs
the system has. CPU hotplug can offline a CPU at runtime and causing the
offline CPU not present in /proc/stat if we only show online cpu in
/proc/stat.

Change-Id: I4fd0cfcdb174244044634389da2fbdef77744c19
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>