i965/fs: Stop relying on param_size in assign_constant_locations

i965/fs: Stop relying on param_size in assign_constant_locations

Now that we have MOV_INDIRECT opcodes, we have all of the size information
we need directly in the opcode.  With a little restructuring of the
algorithm used in assign_constant_locations we don't need param_size
anymore.  The big thing to watch out for now, however, is that you can have
two ranges overlap where neither contains the other.  In order to deal with
this, we make the first pass just flag what needs pulling and handle
assigning pull constant locations until later.