[PORT FROM R2] drivers: intel_scu_watchdog: use scu access for timer; don't use regs

[PORT FROM R2] drivers: intel_scu_watchdog: use scu access for timer; don't use regs

BZ: 19331

- Remove all regiser access; use scu commands discussed at 1/6/12 meeting
- Create ioctl to set all the thresholds, stop/start the WD
- Add support for MSI #6
- Cleaning

Change-Id: I5d88e9b92e567b4e6393bdac9d0b79d87d65b9b7
Reviewed-on: http://android.intel.com:8080/32817
Reviewed-by: Allyn, Mark A <mark.a.allyn@intel.com>
Reviewed-by: Chotard, Celine <celine.chotard@intel.com>
Tested-by: Chotard, Celine <celine.chotard@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>