mmc: mediatek: fix cannot receive new request when msdc_cmd_is_ready fail

when msdc_cmd_is_ready return fail, the req_timeout work has not been
inited and cancel_delayed_work() will return false, then, the request
return directly and never call mmc_request_done().

so need call mod_delayed_work() before msdc_cmd_is_ready()

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>