msm: kgsl: Refactor the GPU target list

Move the list of GPU targets from a static array to a set of structs. This
allows us to create target specific structures which are more flexible and
allows us to expand the size and scope of the GPU description for each
target family.

Change-Id: Ic0dedbade9e69bb4c4148dc0e826171a5f558d11
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>