mmc: sdhci-esdhc-imx: Enable support for system wakeup for SDIO

Enable support for system wakeup, by setting the wakeup capability for the
slot corresponding to the SDIO card. Users need to enable the wakeup
through the sysfs interface.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/1623326486-25275-1-git-send-email-haibo.chen@nxp.com


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