Fix one misspelling of "device tree" to "devicetree"
Fix one misspelling of "device tree" to "devicetree"

As the standard spelling is clearly "devicetree" (all one word), fix
the one example of "device tree" in the entire source.

Signed-off-by: Robert P. J. Day <01aa5cd9a29907856ec6ddeebcb643ede4c45b8b@crashcourse.ca>
Signed-off-by: Rob Herring <fbb37eacae100e13076d5c4b46f06cfa4d6fa9f8@kernel.org>

devicetree-org/devicetree-specification