drivers/rtc/rtc-s3c.c: convert to use devm_* API

rtc-s3c driver is modified to use devm_request_and_ioremap() (combining
request_mem_region and ioremap), devm_clk_get() and devm_request_irq()
APIs.  Since this removes the necessity of freeing the related resources
the return path is also simplified.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>