[nrf noup] platform: Disable warning for null dereferece

When building the TF-M PSA tests:
west build -p -b nrf9160dk/nrf9160/ns -T tfm.psa_test_storage_lvl1 .

This produces a warning inside the Nordic HAL.

This commit can be dropped if the warning does not appear in the
next version of the HAL.

Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>

Author: Vge0rge

platform/ns/toolchain_ns_GNUARM.cmake

@@ -79,7 +79,7 @@ add_compile_options(
     -Wno-format
     -Warray-parameter
     -Wno-unused-but-set-variable
-    -Wnull-dereference
+     #-Wnull-dereference
     -Wno-error=incompatible-pointer-types
     -fdata-sections
     -ffunction-sections