ASoC: codecs: bolero: Fix playback issue over RX1

Mono playback over RX1 is not happening due to
incorrect channel mask sent to AFE. Update
channel mask for RX to enable playback.

Change-Id: I06eeb565149c635ddbcce39f4260f67b80474335
Signed-off-by: Vatsal Bucha <vbucha@codeaurora.org>