ASoC: msm: 8939: schedule mbhc start after 4sec

mbhc initial calibration needs mclk to be enabled, so schedule
headset detection for 4sec so that modem gets loaded and will be ready
to accept mclk enable request command.

Change-Id: I19d07f5c4d9b35cbff3df72ebf7cdff99419d38e
Signed-off-by: Yeleswarapu Nagaradhesh <nagaradh@codeaurora.org>