ARM: dts: stm32: Adjust PLL4 settings on AV96

The PLL4 is supplying SDMMC12, SDMMC3 and SPDIF with 120 MHz and
FDCAN with 96 MHz. This isn't good for the SDMMC interfaces, which
can not easily divide the clock down to e.g. 50 MHz for high speed
SD and eMMC devices, so those devices end up running at 30 MHz as
that is 120 MHz / 4. Adjust the PLL4 settings such that both PLL4P
and PLL4R run at 100 MHz instead, which is easy to divide to 50MHz
for optimal operation of both SD and eMMC, SPDIF clock are not that
much slower and FDCAN is also unaffected.

Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>