mmc: rtsx: swap function position to avoid pre declaration

move function sd_read_data()/sd_write_data() behind
sd_send_cmd_get_rsp() to avoid pre-declaration.

Signed-off-by: Micky Ching <micky_ching@realsil.com.cn>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>