rtc-r9701.c: silence compiler warning

Commit 75b61022

 ("rtc: add support for
Epson RTC-9701JE V4") introduced the warning

  drivers/rtc/rtc-r9701.c: In function `r9701_get_datetime':
  drivers/rtc/rtc-r9701.c:74: warning: unused variable `time'

Signed-off-by: S.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>