msm: kgsl: Clean-up for SPTP PC enable/disable

Use the right flag in the sysfs enable/disable.  Explicitly
set the default register values on regulator enable.

Change-Id: Id7c1326083cecb976688cb60011c76464654e6f1
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>