mmc: sdhci-esdhc-imx: remove ESDHC_CD_GPIO handling from IO accessory

With commit 9444e07 (mmc: remove unncessary mmc_gpio_free_cd() call from
slot-gpio users) in place, the ESDHC_CD_GPIO handling in IO accessories
becomes unnecessary.  Remove it.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>