af_vsock: Remove unused declaration vsock_release_pending()/vsock_init_tap()

Commit d021c344 ("VSOCK: Introduce VM Sockets") declared but never implemented
vsock_release_pending(). Also vsock_init_tap() never implemented since introduction
in commit 531b3748 ("VSOCK: Add vsockmon tap functions").

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20230803134507.22660-1-yuehaibing@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>