Revert "ipv6: set rt6i_protocol properly in the route when it is installed"

This reverts commit 23e983e2 which is
commit b91d532928dff2141ea9c107c3e73104d9843767 upstream.

It breaks the Android networking test suite, which works fine with the
backported patch in 4.14.  So something must be off for 4.9 for this
patch, so just revert it.

Cc: Jianlin Shi <jishi@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>