ARM: davinci: da8xx: remove hard coding of rtc device wakeup

Since now rtc-omap driver itself calls deice_init_wakeup(dev, true),
duplicate call from the rtc device registration can be removed.

This is basically a partial revert of the prev commit

commit 75c99bb0006ee065b4e2995078d779418b0fab54
Author: Sekhar Nori <nsekhar@ti.com>

    davinci: da8xx/omap-l1: mark RTC as a wakeup source

Signed-off-by: Hebbar Gururaja <gururaja.hebbar@ti.com>
Acked-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>