dt-bindings: battery: Add trickle-charge upper limit

Some of the chargers for lithium-ion batteries use a trickle-charging as
a first charging phase for very empty batteries, to "wake-up" the battery.
Trickle-charging is a low current, constant current phase. After the
voltage of the very empty battery has reached an upper limit for
trickle charging, the pre-charge phase is started with a higher current.

Allow defining the upper limit for trickle charging voltage, after which
the charging should be changed to the pre-charging.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/9c3064ec7e32cda442336bf633fb93355ce6a97d.1765804226.git.mazziesaccount@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>