usb: type_c: pericom: Allow enabling chip using GPIO

Driver currently assumes that ENB pin of Pericom chip
is connected to one of the GND pin of type-c receptacle.
Though this allows automatically enabling pericom chip
on plug insertion, but this is recommended by hardware
team due to side effects of leaving a receptacle pin
floating. In addition to this, as per pericom HPG, chip
is reset only on Power-On and when chip is disabled and
then enabled again using ENB pin then it must be reset
using i2c writes. This indirectly enforces the need
to have software control the ENB pin using GPIO.

Change-Id: Iea14f79fd7e7379a3f338922f497440fef0eee37
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>