mmc: core: Switch to basic workqueue API for sdio_irq_work

The delay parameter isn't set by any user, therefore simplify the code
and switch to the basic workqueue API w/o delay support. This also
reduces the size of struct mmc_host.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/13d8200a-e2a8-d907-38ce-a16fc5ce14aa@gmail.com


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