ARM: dts: stm32: Temporarily drop cd-gpios from AV96 DT

The card-detect GPIO and any other GPIO access currently doesn't work in
U-Boot SPL on any STM32 platform and crashes the SPL. To work around this
problem on AV96 right before release, remove the cd-gpios from DT. This
patch must be reverted right after release, once the proper fix for the
GPIO driver, "gpio: stm32: support gpio ops in SPL", is applied.

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>
Cc: Tom Rini <trini@konsulko.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>