mmc: rtsx_usb_sdmmc: Remove the unneeded result variable

Return the value rtsx_usb_send_cmd() directly instead of storing it in
another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/20220920064648.215375-1-ye.xingchen@zte.com.cn


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>