samples: subsys: nvs on nucleo_g431 requires 6kB for storage partitions

Add the overlay for running the samples/subsys/nvs/ application
on the nucleo_g31rb. Define a 6kB storage_partition at the end
of the 128kB flash.

Signed-off-by: Francois Ramu <francois.ramu@st.com>
1 file changed