drivers/rtc/rtc-ds1742.c: use devm_ioremap_resource()

Replace devm_request_mem_region() and devm_ioremap() with
devm_ioremap_resource().

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>