mmc: mmci: Add sdio enable mask in variant data

This patch adds sdio enable mask in variant data, SOCs like ST have
special bits in datactrl register to enable sdio. Unconditionally setting
this bit in this driver breaks other SOCs like Qualcomm which maps this
bits to something else, so making this enable bit to come from variant
data solves the issue.

Originally the issue is detected while testing WLAN ath6kl on Qualcomm
APQ8064.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>