[PATCH v6 0/3]mmc: implement eMMC4.4 standard HW reset feature

[Chuanxiao Dong <chuanxiao.dong@intel.com>]

Hi all,
   This is the version 6 of hardware reset feature implementation. When eMMC
   card cannot response any command, signal RST_n can help to reset eMMC
   card.

   patch1: enable HW reset capability if card supports.
   patch2: do hardware reset if card occurs read/write/erase timeout
   patch3: implement hwreset_emmc and reinit_emmc callbacks. In this patch,
   hwreset_emmc callback will pull up/down the corresponded GPIO line number
   to trigger RST_n signal.

   change log:
   1. Move hardware_reset callback to mmc_bus_ops so that all kinds of host
   controller can use hardware_reset callback to trigger RST_n signal.
   Different host controller only needs to provide a GPIO line number to
   this callback.
   2. Add GPIO pull up/down part in hardware_reset callback.
   3. Remove reset_emmc callback in sdhci_ops.

Thanks
Chuanxiao