ipa: Set the BSC_FD_WRITE in ipa_client_conn_open

When the link is being created BSC_FD_WRITE and BSC_FD_READ are
being ored into the flag. When the socket connects the first time
the ipa_client_fd_cb function is called and the link->state is
moved from connecting to connect.

In case the connection drops and ipa_client_conn_open is called
again the BSC_FD_WRITE flag might not be set. This means that after
the socket is connected, ipa_client_fd_cb will not be called. This
means that the updown_cb will not be called until after the first
write or read on the socket. It might even lead to missing some
data.

When re-connecting set the write flag again.