mmc: TMIO: Use devm_request_irq()

Clean up resource allocation and freeing.

Signed-off-by: Ian Molton <ian.molton@codethink.co.uk>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>