drivers/rtc/rtc-s3c.c: remove one superfluous rtc_valid_tm() check

s3c_rtc_gettime() already returns the result of rtc_valid_tm() on the
obtained time so get rid of another call to rtc_valid_tm().

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>