mmc: tmio: Mask all IRQs when inactive

To make sure we don't receive any spurious IRQs while we are inactive,
mask the IRQs from within the ->runtime_suspend() callback.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>