package/multipath-tools: fix legal-info

Commit b535fd2a forgot to update hash of
README.md (updates not related to license)

Fixes:
 - http://autobuild.buildroot.org/results/21bc3aa3e1b89ace5aebe771b8c34d5bd0cb9c3d



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>