ARM: dts: stm32: Update sdmmc binding for stm32h743i-eval

Update some sdmmc properties which have been updated with
v4.19 DT bindings:
      - st,dirpol becomes st,sig-dir
      - st,negedge becomes st,neg-edge
      - st,pin-ckin becomes st,use-ckin

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