rtc: pm8xxx: update kerneldoc for struct pm8xxx_rtc

The change from u8 ctrl_reg to const struct pm8xxx_rtc_regs *regs; did not
properly update the kerneldoc comment. Fixes:

drivers/rtc/rtc-pm8xxx.c:64: warning: Function parameter or member 'regs' not described in 'pm8xxx_rtc'

Fixes: c8d523a4 ("drivers/rtc/rtc-pm8xxx.c: rework to support pm8941 rtc")
Link: https://lore.kernel.org/r/20191122102212.400158-7-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-pm8xxx.c

@@ -49,7 +49,7 @@ struct pm8xxx_rtc_regs {
  * @regmap:		regmap used to access RTC registers
  * @allow_set_time:	indicates whether writing to the RTC is allowed
  * @rtc_alarm_irq:	rtc alarm irq number.
- * @ctrl_reg:		rtc control register.
+ * @regs:		rtc registers description.
  * @rtc_dev:		device structure.
  * @ctrl_reg_lock:	spinlock protecting access to ctrl_reg.
  */