Fix this build error when PM_SLEEP is not selected:

drivers/rtc/rtc-mt2712.c:412:10: error: ‘mt2712_pm_ops’ undeclared here (not in a function); did you mean ‘mt2712_rtc_ops’?
  412 |   .pm = &mt2712_pm_ops,
      |          ^~~~~~~~~~~~~

Link: https://lore.kernel.org/r/20200317143421.9551-1-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>