rtc: sh: silence warning

Silence:
drivers/rtc/rtc-sh.c:517:58: warning: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 3 [-Wformat-truncation=]

Link: https://lore.kernel.org/r/20230911095052.1292869-1-alexandre.belloni@bootlin.com


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