oe/license_finder: don't return the "crunched" license text in crunch_license

oe/license_finder: don't return the "crunched" license text in crunch_license

crunch_license() will perform some basic text manipulation to try and
canonicalise the license texts. It also returns the new license text but
none of the callers use this, and as a slightly mangled version of the
original it has no real purpose.

Remove this return value and clean up the callers.

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