mmc: tmio: move finish_request function further down

Plain code move with no changes. Needed for refactoring. Also, looks
nicer if request and finish_request are next to each other.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>