linux-wandboard

ENGR00170626 imx-cs42888: avoid codded gpio reset definition

* Remove hard codded gpio reset definition
* Add in mxc_audio_platform_data reset gpio reference to be able
  to pass gpio reset assignment in board definition file instead
  of a macro for each different board.
* Add plat_data null check, return EINV if no set.

Signed-off-by: Adrian Alonso <aalonso@freescale.com>