hal: Add perf lock only during device switch

Existing Audio HAL acquires perf lock during device switch
for every Android Policy manager routing request without
checking for device switch. Acquire perf lock only when
there is actual device switch and avoid redundant acquiring
of perf locks for every routing request.

Change-Id: If81dde9f2bc5e6553dca1145b5966098712d65db
1 file changed