ASoC: msm: Moving the gpio request and free in probe and exit.

Move the request and free of gpio lines while enabling the
level shifter to the probe and the exit of the cs8427 chip.
Mark the prtd pointer as null in the capture close.

Change-Id: I59d583dce314ffc3ad1eb032c53da8580b65d001
Signed-off-by: Aviral Gupta <aviralg@codeaurora.org>