hal: Restrict SSR recording to channel position representation

Surround Sound Recording(SSR) supports only channel position
representation while default channel mask for multi-channel
recording is always index representation.
Return updated channel mask in case index representation is sent
for channel count 6. This ensures audio flinger reopens the session
with updated position representation channel mask.
And also handled the case if any client requests recording with
multichannel when SSR is not enabled, will check the max_mic_count
supported by the device and update the channel mask accordingly.

Change-Id: Ib925a5f31d50182cd595e547f3412ed809224a5a