recipetool/create: show more of the license path when it can't be identified

recipetool/create: show more of the license path when it can't be identified

If there are multiple source trees in a project (incredibly common with
go-mod, for example) then the relative path of the LICENSE file from
the source tree could just be "LICENSE", which is not useful when there
are tens of files across the recipe with that name.

Show the parent directory name too, to clarify which file is unknown.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>