scripts: kconfigfunctions: Add dt_node_ph_array_prop_int/hex

Add dt_node_ph_array_prop_int/hex function to query value of cells
from a phandle-array property of a node at a given index of the array.

Based on dt_node_array_prop_int/hex.

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>