ARM: dts: stm32: Enable internal pull-ups for SDMMC1 on DHCOM SoM

The default state of SD bus and clock line is logical HI. SD card IO is
open-drain and pulls the bus lines LO. Always enable the SD bus pull ups
to guarantee this behavior on DHCOM SoM. Note that on SoMs with SD bus
voltage level shifter, the pull ups are built into the level shifter,
however that has no negative impact.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>