mmc: core: rewrite mmc_fixup_device()

Currently, mmc_fixup_device() is a bit difficult to read because of
particularly long condition.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/6515c1e8b3aa69ad273726f6e877d85c20f286ad.1636564631.git.hns@goldelico.com


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