It is common to read a device-tree property from the node associated with
a device. Add convenience functions to do this so that drivers do not need
to deal with accessing the ofnode from the device.
These functions all start with 'dev_read_' to provide consistent naming
for all functions which read information from a device's device tree node.
These are inlined when using the flat DT to save code size. The live tree
implementation is added in a later commit.
Signed-off-by: Simon Glass <sjg@chromium.org>
f11c7ab94d