build: don't look up for a pkg-config module twice

There's no parameter after the IMPORTED_TARGET, so these were
interpretted as, e.g., "look for libyang-cpp >= 1.0.0 *and* for
libyang-cpp". That doesn't make much sense, but it dated from some time
long, long ago when I did not read CMake's docs properly.

Change-Id: Ibcb0b6ecd8a967df49db6b8a3c3458cb1d0ba3cb
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 80363f2..421e99c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -84,7 +84,7 @@
     message(STATUS "Skipping sysrepo per configure options")
     set(SYSREPO_FOUND 0)
 else()
-    pkg_check_modules(SYSREPO sysrepo-cpp>=1.0.0 IMPORTED_TARGET sysrepo)
+    pkg_check_modules(SYSREPO sysrepo-cpp>=1.0.0 IMPORTED_TARGET)
 endif()
 
 if(SYSREPO_FOUND)