sysutils/synergy: replace hardcoded path for evdev.xml

PR: 271200
Reported by: Koine Yuusuke <koinec@yahoo.co.jp>
Tested by: Koine Yuusuke <koinec@yahoo.co.jp>
Reviewed by: meta
Approved by: maintainer timeout (> 4 months)

(cherry picked from commit 755d5c1bfec3e50b4b6b4fce895dc992c568f5a9)