of: overlay: reorder fields in struct fragment

Order the fields of struct fragment in the same order as
struct of_overlay_notify_data.  The order in struct fragment is
not significant.  If both structs are ordered the same then when
examining the data in a debugger or dump the human involved does
not have to remember which context they are examining.

Tested-by: Alan Tull <atull@kernel.org>
Signed-off-by: Frank Rowand <frank.rowand@sony.com>