recipetool: Add support for linenumbers to licenses.csv

recipetool: Add support for linenumbers to licenses.csv

Add support for linenumbers (begin and end lines) to licenses.csv. Add
an optional linenumbers parameter to get_license_md5sums to support
different use cases.

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>