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: I767efd05f8b5aa5d9259d95f6f11d7670af74d81