ARM: dts: stm32: Fix GPIO hog flags on DHCOM DRC02

The GPIO hog flags are ignored by gpiolib-of.c now, set the flags to 0.
Since GPIO_ACTIVE_HIGH is defined as 0, this change only increases the
correctness of the DT.

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