scsi: ufs: Initialize extcon before scsi for UFS card

Since the implementation of UFS card hot plug depends on extcon framework,
make sure the extcon is probed before UFS card so that its probe is not
deferred everytime during bootup.

Change-Id: Ie76ae5a2ef0c06e97b86c3347a2d58329219b53e
Signed-off-by: Can Guo <cang@codeaurora.org>