The rtc-omap driver currently hardcodes the RTC to be
not capable of wakeup events. On the DA850/OMAP-L138
SoC, the RTC is a wake up source from its "deep sleep"
mode.

Let platform data set the wakeup capability flag instead.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>