systemd: enable on the ARC architecture

ARC port was merged in v234, see
https://github.com/systemd/systemd/commit/27b09f1f1ed29edb9c52ad8414c2344974a07a23

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/systemd/Config.in

@@ -5,7 +5,7 @@ config BR2_PACKAGE_SYSTEMD_ARCH_SUPPORTS
 		BR2_mipsel || BR2_powerpc || BR2_powerpc64 || \
 		BR2_powerpc64le || BR2_sh4 || BR2_sh4eb || \
 		BR2_sh4a || BR2_sh4aeb || BR2_sparc || BR2_x86_64 || \
-		BR2_aarch64 || BR2_m68k
+		BR2_aarch64 || BR2_m68k || BR2_arc
 
 menuconfig BR2_PACKAGE_SYSTEMD
 	bool "systemd"