ASoC: mdm9625: Avoid setting DAI mode multiple times

MI2S start up function sets DAI format mode multiple
times. Since MI2S Rx and Tx are linked, it is required
that mode is not set when one of the interface is
already active. This fix avoids setting mode multiple
times.

Change-Id: I90e99e638d7f93ceed74cb1f33ccf1fb44b03b25
Signed-off-by: Venkat Sudhir <vsudhir@codeaurora.org>