power: supply: bq25890: Factor out regulator registration code

power: supply: bq25890: Factor out regulator registration code

[ Upstream commit 5f5c10ecaf3fdeba9b2b0af5301977420c2c4df0 ]

Pull the regulator registration code into separate function, so it can
be extended to register more regulators later. Currently this is only
moving ifdeffery into one place and other preparatory changes. The
dev_err_probe() output string is changed to explicitly list vbus
regulator failure, so that once more regulators are registered, it
would be clear which one failed.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Stable-dep-of: a7aaa80098d5 ("power: supply: bq25890: Ensure pump_express_work is cancelled on remove")
Signed-off-by: Sasha Levin <sashal@kernel.org>