power: collie_battery: hide unused variable

power: collie_battery: hide unused variable

The 'wakeup_enabled' variable in this driver is only accessed
by the optional power management functions and we get a warning
when they are disabled:

drivers/power/collie_battery.c:29:12: error: 'wakeup_enabled' defined but not used [-Werror=unused-variable]

This moves the definition next to the users inside the same #ifdef,
which avoids the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>