package/stella: fix legal-info

package/stella: fix legal-info

Commit a7210c24e343a13e58d1d45b7e0c4bdb51854857 forgot to update hash of
Copyright which has changed due to update in year:

https://github.com/stella-emu/stella/commit/275666b0af3e029b44be7e676526b8172da44736
https://github.com/stella-emu/stella/commit/9ad47ae5f3457693944a3754432ff1236c67203c

While at it, update indentation of hash file to two spaces

Fixes:
 - http://autobuild.buildroot.org/results/38fa47221f36f3db603ee54c86b9747b0c6ca5d7

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>