[tegra ALSA] Enable mic jack detection

[tegra ALSA] Enable mic jack detection

Added support on Mic jack detection on Tegra.

- External mic jack detection could be probed by trigger an interrupt
  via specific gpio or pull-up a generic gpio pin. The patch enabled the
  later option.

- Tegra reference boards have gpio to switch external mic and internal
  mic. The switching is done in the patch automatically once jack
  happened.

fixes bug 766757

Change-Id: If530f237d4564d1de6c019b206910f2a0ffe4163
Reviewed-on: http://git-master/r/22033
Reviewed-by: Chao Jiang <chaoj@nvidia.com>
Tested-by: Chao Jiang <chaoj@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Reviewed-by: Scott Peterson <speterson@nvidia.com>