EDP: add userspace knob to update ESR value

EDP: add userspace knob to update ESR value

This patch adds a sysfs entry /sys/power/sysedp/batmon/esr. This
allows an user space process to update the current ESR value seen by
the sysedp_batmon_calc component.

sysedp_batmon_calc will compute the ratio between internal table based
ESR estimate and value set from user space. This ratio will be then
used to scale all future table based ESR estimations.

Bug 1400509

Change-Id: Ia409826f793afef4e4c8d1e42010ff31e529f827
Signed-off-by: Timo Alho <talho@nvidia.com>
Reviewed-on: http://git-master/r/337378
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Sivaram Nair <sivaramn@nvidia.com>
Reviewed-by: Steve Rogers <srogers@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>