mmc: sdio: Change macro names for Marvell 8688 modules

Add underscore as separator in Marvell 8688 macro names for better
readability and consistency.

Signed-off-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20200522144412.19712-3-pali@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Ganapathi Bhat <ganapathi.bhat@nxp.com>