There are various places where we want to extract an unsigned long
value from a device-tree property that can be 1 or 2 cells in length.
This replaces some open-coded calculations, and one place where we
assumed without checking that properties were the length we wanted,
with a little of_read_ulong() helper.
Signed-off-by: Paul Mackerras <paulus@samba.org>
a4dc7ff089