Changed default buffer usage type

dEQP was expecting default buffer usage to be GL_STATIC_DRAW
instead of GL_DYNAMIC_DRAW, so it was changed accordingly.

Change-Id: I5c9e31fc0791955fd32333c1479e76fbc79951a1
Reviewed-on: https://swiftshader-review.googlesource.com/3631
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>