Modify the Makefile to include '$(PREFIX)/bin/systemctl' in the list of paths.
This makes the udev intgeration work as intended when using systemd.

Signed-off-by: Sol Bekic <s+removethis@s-ol.nu>

diff --git a/Makefile b/Makefile
index 22bd0e0..72321a4 100755
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@
	install -D --mode=755 usb_modeswitch_dispatcher $(SBINDIR)/usb_modeswitch_dispatcher
	install -d $(DESTDIR)/var/lib/usb_modeswitch
	test -d $(UPSDIR) -a -e /sbin/initctl && install --mode=644 usb-modeswitch-upstart.conf $(UPSDIR) || test 1
-	test -d $(SYSDIR) -a \( -e /usr/bin/systemctl -o -e /bin/systemctl \) && install --mode=644 usb_modeswitch@.service $(SYSDIR) || test 1
+	test -d $(SYSDIR) -a \( -e /usr/bin/systemctl -o -e /bin/systemctl -o -e $(PREFIX)/bin/systemctl \) && install --mode=644 usb_modeswitch@.service $(SYSDIR) || test 1
 
 install: install-script