mmc: mmci: Drop qcom specific header file

It seems a bit silly to have a header file to share only the
qcom_variant_init() function. So, let's just drop it and move the
declaration of the function into the common mmci.h instead.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>