drivers/rtc/rtc-tps6586x.c: device wakeup flags correction

Use device_init_wakeup() instead of device_set_wakeup_capable() and move
it before rtc dev registering.  This fixes alarmtimer not registered
when tps6586x rtc is the only wakeup compatible rtc in the system.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>