package/xen: fix hash of license file

package/xen: fix hash of license file

Xen was bumped from 4.12 to 4.13 in commit
268e5689b5219890df8cec6e77f8783a8d1f95a3, but the license file hash
was not updated. However, the license file has changed, with a new
paragraph about the Sphinx documentation being licensed under CC-BY
4.0 was added.  Update the SHA to match the new license.

Take this opportunity to re-align the hashes.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>