The STM32H7, STM32F7, STM32L4 and common STM32 SDIO/SDMMC drivers failed
to program the WIDBUS bits when switching MMC/eMMC cards to 4-bit mode,
and the MMC transfer clock presets were hardwired to 1-bit bus width.
Add CLOCK_MMC_TRANSFER_4BIT to the common SDIO clock enum, add 4-bit
MMC clock presets, and update stm32_widebus() to use modifyreg32/
sdmmc_modifyreg32 to set the host controller bus width.
Signed-off-by: DuoYuWang <thirteenking.wang@gmail.com>