power: supply: ab8500: Fix use-after-free in power_supply_changed()

power: supply: ab8500: Fix use-after-free in power_supply_changed()

Using the `devm_` variant for requesting IRQ _before_ the `devm_`
variant for allocating/registering the `power_supply` handle, means that
the `power_supply` handle will be deallocated/unregistered _before_ the
interrupt handler (since `devm_` naturally deallocates in reverse
allocation order). This means that during removal, there is a race
condition where an interrupt can fire just _after_ the `power_supply`
handle has been freed, *but* just _before_ the corresponding
unregistration of the IRQ handler has run.

This will lead to the IRQ handler calling `power_supply_changed()` with
a freed `power_supply` handle. Which usually crashes the system or
otherwise silently corrupts the memory...

Note that there is a similar situation which can also happen during
`probe()`; the possibility of an interrupt firing _before_ registering
the `power_supply` handle. This would then lead to the nasty situation
of using the `power_supply` handle *uninitialized* in
`power_supply_changed()`.

Commit 1c1f13a006ed ("power: supply: ab8500: Move to componentized
binding") introduced this issue during a refactorization. Fix this racy
use-after-free by making sure the IRQ is requested _after_ the
registration of the `power_supply` handle.

Fixes: 1c1f13a006ed ("power: supply: ab8500: Move to componentized binding")
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/ccf83a09942cb8dda3dff70b2682f2c2e9cb97f2.1766268280.git.waqar.hameed@axis.com
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>