drivers/rtc/Kconfig: Let several drivers depend on HAS_IOMEM to avoid compiling issue

Some drivers need 'devm_ioremap_resource' or 'devm_ioremap' which need
HAS_IOMEM, so let them depend on it.

The related error (with allmodconfig under score):

    MODPOST 1365 modules
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-xgene.ko] undefined!
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-stk17ta8.ko] undefined!
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-ds1742.ko] undefined!
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-ds1553.ko] undefined!
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-ds1511.ko] undefined!
  ERROR: "devm_ioremap_resource" [drivers/rtc/rtc-ds1286.ko] undefined!
  ERROR: "devm_ioremap" [drivers/rtc/rtc-rp5c01.ko] undefined!
  ERROR: "devm_ioremap" [drivers/rtc/rtc-msm6242.ko] undefined!
  ERROR: "devm_ioremap" [drivers/rtc/rtc-m48t59.ko] undefined!
  ERROR: "devm_ioremap" [drivers/rtc/rtc-m48t35.ko] undefined!
  ERROR: "devm_ioremap" [drivers/rtc/rtc-bq4802.ko] undefined!

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>