openvswitch: use default rundir /var/run/openvswitch/

This subdir contains multiple pid, unix domain socket files.  It's a
custom to put them in it's own subdir

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

net/openvswitch/Makefile

@@ -146,7 +146,6 @@ define KernelPackage/openvswitch/description
   module. Furthermore, it supports OpenFlow.
 endef
 
-CONFIGURE_ARGS += --with-rundir=/var/run
 CONFIGURE_ARGS += --enable-ndebug
 CONFIGURE_ARGS += --disable-ssl
 CONFIGURE_ARGS += --enable-shared