mmc: sdio: fix a typo in the comment of SDIO_SD_REV_3_00

I believe "Spev" is typo, should be "Spec".

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/20210311174157.561dada9@xhacker.debian
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>