drivers/rtc/rtc-omap.c: remove multiple device id checks

Remove multiple superfluous device id checks.  Since an id_table is
present in the driver probe() should never encounter an empty device id
entry.  In case of OF style match, of_match_device() returns an matching
entry.

For paranoia sake, check for device id entry once and fail probe() if none
is found.  This is much better than checking for it multiple times.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>