Input: snvs_pwrkey - add clk handling

Input: snvs_pwrkey - add clk handling

[ Upstream commit d997cc1715df7b6c3df798881fb9941acf0079f8 ]

On i.MX7S and i.MX8M* (but not i.MX6*) the pwrkey device has an
associated clock. Accessing the registers requires that this clock is
enabled. Binding the driver on at least i.MX7S and i.MX8MP while not
having the clock enabled results in a complete hang of the machine.
(This usually only happens if snvs_pwrkey is built as a module and the
rtc-snvs driver isn't already bound because at bootup the required clk
is on and only gets disabled when the clk framework disables unused clks
late during boot.)

This completes the fix in commit 135be16d3505 ("ARM: dts: imx7s: add
snvs clock to pwrkey").

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211013062848.2667192-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>