mmc: dw_mmc: add the "reset" as name of reset controller

Add the "reset" as name of reset controller.
This is for preventing the wrong operation. Even if some SoC has reset
controller, doesn't define "resets" in device-tree.
Then it might be waiting for reset controller and it should be stuck.

Fixes: d6786fef

 ("mmc: dw_mmc: add reset support to dwmmc host controller")
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>