mmc: core: Fix indentation

sdio_single_irq_set() was indented with a mix of tabs and spaces.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200221163147.608677-1-Jerome.Pouiller@silabs.com


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