Fix the following build issue:

drivers/rtc/rtc-imx-sc.o: In function `imx_sc_rtc_set_time':
>> rtc-imx-sc.c:(.text+0x212): undefined reference to `__arm_smccc_smc'

Fixes: 13a929f3 ("rtc: imx-sc: add rtc set time support")
Reviewed-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>