msm: mdss: Remove regulator supply type parameter

The I/O utility library has helper function to configure
regultor supplies used by different modules. The regulator
type parameter associated with a supply regulator specifies
whether it is possible to set voltage levels for that regulator.
This change removes the need to specify the regulator type as
this can be easily determined by calling corresponding regulator
API.

Change-Id: I73aff82a0d04920cd5dd5150aeb34edecc305e85
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>