mmc: sdhci: R1B command handling + MMC_CAP_ERASE.

ERASE command needs R1B response, so fix R1B-type command
handling for SDHCI controller. For non-DAT commands using a busy
response, the cmd->cmd_timeout_ms (in ms) field is used for timeout
calculations.

Based on patch by Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Andrei Warkentin <andreiw@motorola.com>
Signed-off-by: Chris Ball <cjb@laptop.org>