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>