Analysis: RT_USING_RTC preprocessing is used in 47cd52d ("修复不
使能 RT_USING_DEVICE 时编译报错") to control the reference of
rtdevice.h, as well as the implementation and call of _control_rtc,
but there are some omissions.
Solution: Add RT_USING_RTC preprocessing control to missing
_control_rtc
Signed-off-by: Shicheng Chu <1468559561@qq.com>
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
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