drivers/rtc/rtc-ds1307.c: fix sysfs wakealarm attribute creation

In order to allow the creation of the sysfs attribute wakealarm, this
patch moves the device_set_wakeup_capable() call above the RTC device
registration.

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>