configure.ac: correctly check for libdrm_radeon version
diff --git a/configure.ac b/configure.ac
index 46938f4..9c6ce3f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -818,7 +818,7 @@
 AC_SUBST([HAVE_XF86VIDMODE])
 
 PKG_CHECK_MODULES([LIBDRM_RADEON],
-		  [libdrm_radeon libdrm >= $LIBDRM_RADEON_REQUIRED],
+		  [libdrm_radeon >= $LIBDRM_RADEON_REQUIRED],
 		  HAVE_LIBDRM_RADEON=yes,
 		  HAVE_LIBDRM_RADEON=no)