recipetool: create: Improve identification of licenses

recipetool: create: Improve identification of licenses

Rather than having a static list of crunched MD5 checksums for some of
the most common licenses, calculate it for all common licenses. This
should improve the identification of license text variantions.

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>