layerscape: fdt.c: Check for NULL return value from fdt_getprop()

Check for NULL return value from fdt_getprop() in
fdt_fixup_remove_jr()

Signed-off-by: Priyanka Singh <priyanka.singh@nxp.com>
[Fixed checkpatch errors/warnings]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>