asoc: Set and get lsm port indices on a per session basis

When multiple LSM sessions are running, lsm port index might
be overwritten with index of different sessions during
concurrent LPI and Non LPI session switches. Maintain
lsm port index on a per session basis to avoid this issue.

Change-Id: I943ea7899b977e06f467a140a9d1c9feb31c58bd
Signed-off-by: Aditya Bavanari <abavanar@codeaurora.org>