rtc: ds1685: use EXPORT_SYMBOL_GPL for ds1685_rtc_poweroff

ds1685_rtc_poweroff is only used externally via symbol_get, which was
only ever intended for very internal symbols like this one.  Use
EXPORT_SYMBOL_GPL for it so that symbol_get can enforce only being used
on EXPORT_SYMBOL_GPL symbols.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Joshua Kinard <kumba@gentoo.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Author: Christoph Hellwig

drivers/rtc/rtc-ds1685.c

@@ -1432,7 +1432,7 @@ ds1685_rtc_poweroff(struct platform_device *pdev)
 		unreachable();
 	}
 }
-EXPORT_SYMBOL(ds1685_rtc_poweroff);
+EXPORT_SYMBOL_GPL(ds1685_rtc_poweroff);
 /* ----------------------------------------------------------------------- */