[PORT FROM R2] The slew rate of VC motor current rising time has changed.

[PORT FROM R2] The slew rate of VC motor current rising time has changed.

BZ: 17272

Currently VC motor has '0' in both configuration registers: 'slew_rate' and 'vcm_step_time'.
Therefore a current in the VC motor rises very fast (instantaneous) and it causes a big
mechanical impact to the lens unit, audible as a loud click.

This patch makes VC current rising slope slightly inclined and it makes a lens movement to be
more smooth. Patch should not affect to the speed of AF, because a duration of single Af step
remains the same.

Change-Id: Ibda9f7af5cdd74287bb25ddb83c53fa4dbaf1248
Orig-Change-Id: Ie35b30cafa9848a7175798a3832bd06be511aec8
Signed-off-by: Vitali Samurov <vitali.samurov@intel.com>
Reviewed-on: http://android.intel.com:8080/22776
Reviewed-by: Koski, Anttu <anttu.koski@intel.com>
Tested-by: Koski, Anttu <anttu.koski@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
Reviewed-on: http://android.intel.com:8080/28041
Reviewed-by: Tuominen, TeemuX <teemux.tuominen@intel.com>