audio: fix memory corruption.

Race condition:

There is a race condition between audio primary hal thread and soundtrigger
hal thread when they want to get snd_card number.

Memory leakage:

my_data.kvpairs in platforom_info_init function doesn't be destroyed
when use str_parms_create().

Bug: 119328981
Test: manual audio test

Change-Id: Ib86b3cf986a7213007bf9f073ef714a02b28a111
Signed-off-by: juyuchen <juyuchen@google.com>