drivers/rtc/rtc-ds1685.c: fix sparse warnings

Fix two minor sparse warnings:

  CHECK   drivers/rtc/rtc-ds1685.c
  drivers/rtc/rtc-ds1685.c:2178:1: warning: function 'ds1685_rtc_poweroff' with external linkage has definition
  drivers/rtc/rtc-ds1685.c:802:23: warning: Using plain integer as NULL pointer

Fixes: aaaf5fbf56 ("rtc: add driver for DS1685 family of real time clocks")
Signed-off-by: Joshua Kinard <kumba@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-ds1685.c

@@ -799,7 +799,7 @@ ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
 	u8 ctrla, ctrlb, ctrlc, ctrld, ctrl4a, ctrl4b, ssn[8];
-	char *model = '\0';
+	char *model;
 #ifdef CONFIG_RTC_DS1685_PROC_REGS
 	char bits[NUM_REGS][(NUM_BITS * NUM_SPACES) + NUM_BITS + 1];
 #endif
@@ -2174,7 +2174,7 @@ module_exit(ds1685_rtc_exit);
  * ds1685_rtc_poweroff - uses the RTC chip to power the system off.
  * @pdev: pointer to platform_device structure.
  */
-extern void __noreturn
+void __noreturn
 ds1685_rtc_poweroff(struct platform_device *pdev)
 {
 	u8 ctrla, ctrl4a, ctrl4b;