rtc ds1307: ds_1340 change init

For DS140, clear the oscillator fault flag as needed.

Signed-off-by: Frederic RODO <f.rodo@til-technologies.fr>
[ And remove some "sparse" warnings. ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>