ASoC: wcd: enable supply after impedance detection

Enable micbias or current source after impedance detection.
As impedance detection disables sources, if we enable supplies
before impedance detection, it is resulting in improper cable
detection due to repeated enable and disable of sources.

CRs-Fixed: 787909
Change-Id: If7d2664109edda57fd93dd456bda86e288a93772
Signed-off-by: Yeleswarapu Nagaradhesh <nagaradh@codeaurora.org>