Use STMP_OFFSET_REG_(SET|CLR) instead of defining _SET and _CLR for
STMP3XXX_RTC_CTRL and STMP3XXX_RTC_PERSISTENT0 - no functional changes.
Signed-off-by: Harald Geyer <harald@ccbib.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>