Add the following stats.
- Number of Spectral events received from the target
- Number of consume_spectral_report() invocations
- Number of fill_samp_msg() invocations
- Number of SAMP messages that are ready to be sent to the user-space
- Number of SAMP messages queued to the user-space
Change-Id: I53fda4b309620043a77bc2bc87573941d7fb0bcb
CRs-Fixed: 3156151