package/systemd: fix license hash

Bump to 243.4 forgot to update hash of README file (update to the
requirements).

Fixes:
 - http://autobuild.buildroot.org/results/eae13046b90253cdb2bf260e10b316386dff4eb1

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr: explain why README was changed]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/systemd/systemd.hash

@@ -2,4 +2,4 @@
 sha256	281bc47aa6b173c3c6fa1bbc88aea84ecb014313aeb679c54f8885dd09e434be	systemd-243.4.tar.gz
 sha256	ab15fd526bd8dd18a9e77ebc139656bf4d33e97fc7238cd11bf60e2b9b8666c6	LICENSE.GPL2
 sha256	dc626520dcd53a22f727af3ee42c770e56c97a64fe3adb063799d8ab032fe551	LICENSE.LGPL2.1
-sha256	3a3b3cbd0ef03c7045bfda9b61062bdc33ad4913b44a6b6147043f26d00b51bf	README
+sha256	ff5a9e3791e3a941a2d85b5ef7ad7c01441dd42f4c760bff2c8b086c7d764885	README