mmc: stm32_sdmmc2: update pwron management

Correctly manage the SDMMC reset and card cycle power
to fully handle the power cycle added in the MMC uclass
and avoid issue with level-shifter with some uSDCARD.

3 states managed in driver:
  1/ reset: SDMMC disable, signal HiZ
  2/ power-cycle: SDMMC disable, signals drive to 0
  3/ power-on: SDMMC enabled

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
1 file changed