asoc: codecs: Use sysfs instead of mixer_ctls for EP92 HDMI

The format change event signaling for EP92 HDMI input is adapted
to provide format information through sysfs nodes.
Chip configuration is done through sysfs as well.

Change-Id: I8c930ca5647899b4434272009699763c32fe9d04
Signed-off-by: Ralf Herz <rherz@codeaurora.org>
Signed-off-by: Mangesh Kunchamwar <mangeshk@codeaurora.org>