dsp: afe topology deregister

To handle erroneous sequence when HLOS audio driver registers
a FFNS topology in non-island mode instead of island mode:
Call afe topology deregister to deregister any previously
created topology before registering the topology.

Change-Id: Iff871da998847ea5d3bcee417c780b8acaf70ca3
Signed-off-by: Sanjana B <sanjb@codeaurora.org>