openvswitch: python: remove openvswitch as a dependency

The python library is a standalone unit.  Remove dependency on
PACKAGE_openvswitch to allow users to use it with maybe remote
openvswitch services.

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

net/openvswitch/Makefile

@@ -102,7 +102,7 @@ endef
 define Package/openvswitch-python
   $(call Package/openvswitch/Default)
   TITLE:=Open vSwitch Python Support
-  DEPENDS:=+openvswitch +PACKAGE_openvswitch-python:python +PACKAGE_openvswitch-python:python-six
+  DEPENDS:=+PACKAGE_openvswitch-python:python +PACKAGE_openvswitch-python:python-six
 endef
 
 define Package/openvswitch-python/description