rtc: optee: make optee_rtc_pm_ops static

Fix sparse warningg:
drivers/rtc/rtc-optee.c:714:1: sparse: sparse: symbol 'optee_rtc_pm_ops' was not
declared. Should it be static?

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509230549.L26lw7UZ-lkp@intel.com/
Link: https://lore.kernel.org/r/20251005201925.3757345-1-alexandre.belloni@bootlin.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>