power: supply: qti_battery_charger: support wireless firmware update

Add support for wireless charger firmware update in battery charger
driver through "wireless_fw_update" and "wireless_fw_force_update"
properties under "/sys/class/qcom-battery". Support firmware update
for wireless charger (IDT9412) for which firmware is split into
multiple chunks (128 bytes each) and sent over PMIC Glink. Charger
firmware running on the remote subsystem does the FW update by
communicating with IDT9412.

Wireless charger firmware name should be specified via a device tree
property "qcom,wireless-fw-name".

To update wireless firmware, user has to push the FW binary to a
firmware partition (e.g. /vendor/firmware) and then do one of the
following.

Normal update for which FW version check is made:

 # echo 1 > /sys/class/qcom-battery/wireless_fw_update

Forced update for which FW version check is skipped:

 # echo 1 > /sys/class/qcom-battery/wireless_fw_force_update

To read back FW version:

 # cat /sys/class/qcom-battery/wireless_fw_version

Change-Id: Id565e7d5a73041d6e0340edc66eb8b1615396435
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>