ProcessCpuTracker: Fix ArrayIndexOutofBoundsException in tempSpeeds

If time_in_state file is not available mCpuSpeeds is created with size 0
and subsequent call if the file becomes available there is an
ArrayIndexOutofBoundsException.
This change avoids the crash by breaking out of the loop, also adds error
logging

CRs-Fixed: 553569
Change-Id: Id5e219ca1cd3f058f714aecd5902ec2f6c11ae03