of: overlay: Reorder struct fragment fields kerneldoc

The fields of the fragment structure were reordered, but the kerneldoc
was not updated.

Fixes: 81225ea6

 ("of: overlay: reorder fields in struct fragment")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/cfa36d2bb95e3c399c415dbf58057302c70ef375.1695893695.git.geert+renesas@glider.be
Signed-off-by: Rob Herring <robh@kernel.org>