si-tools: FM configuration improvements

si-tools: FM configuration improvements

This commit is removed from meta-renesas-rcar-gen3

====
commit a5dfadaa3931977a221e0508354e9ab97482b9ab
Author: Scott Murray <scott.murray@konsulko.com>
Date:   Thu Dec 21 20:46:30 2017 -0500
====

Some changes to allow integration with the AGL radio binding and
improve FM configuration with some tweaks and additional configuration
options.

Changes include:
- Add command-line option for selecting FM band plan.  The default
  band plan is US / Canada.
- Add command-line options for setting FM scanning valid SNR and RSSI
  thresholds to allow tweaking sensitivity in poor radio environments.
- Increased seeking scan timeout to 3 seconds, which seems to improve
  behavior in poor radio environments where powerful stations may be
  far apart.
- Removed explicit setting of FM_SOFTMUTE_SNR_LIMITS, as it seemed
  like it might be resulting in odd muting behavior when scanning.
- Changed initial FM frequency if not specified to the minimum of the
  band plan.

Change-Id: I5d8c95947489b83384babb50285b76d3de45214a
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Signed-off-by: Harunobu Kurokawa <harunobu.kurokawa.dn@renesas.com>