power: bq24190_charger: mark PM functions as __maybe_unused

Without CONFIG_PM, we get a harmless warning:

drivers/power/supply/bq24190_charger.c:1514:12: error: 'bq24190_runtime_resume' defined but not used [-Werror=unused-function]
drivers/power/supply/bq24190_charger.c:1501:12: error: 'bq24190_runtime_suspend' defined but not used [-Werror=unused-function]

To avoid the warning, we can mark all four PM functions as __maybe_unused,
which also lets us remove the incorrect #ifdef.

Fixes: 3d8090cba638 ("power: bq24190_charger: Check the interrupt status on resume")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Liam Breck <kernel@networkimprov.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>