Revert "wic: plugins source bootimage/isoimage rename to allow be imported"
This reverts commit ee5a56e13ffa442de2d942dbc56be0dc00d41adf.
(From OE-Core rev: b40fd6d733e4c73bb12d520fcb8958151f089aec)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>