package/systemd: update BR2_PACKAGE_SYSTEMD_ARCH_SUPPORTS

package/systemd: update BR2_PACKAGE_SYSTEMD_ARCH_SUPPORTS

systemd supports:
 - nios2 since version 230 and
 https://github.com/systemd/systemd/commit/b79660e6acb964f94ddba0ea4e1182215934dfc3
 - riscv sinc version 232 and
 https://github.com/systemd/systemd/commit/171b53380085b1288b03b19a2b978f36a5c003d0
 - aarch64_be (tested with qemu_aarch64_virt_defconfig reconfigured to
 aarch64_be)
 - sparc64 (tested with qemu_sparc64_sun4u_defconfig)
 - mips64 and mips64el (tested with qemu_mips64el_malta_defconfig)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>