i965/fs: Set the header_size on LOAD_PAYLOAD in opt_sampler_eot

Commit 94ee908448 added a header size parameter to the function to
create the LOAD_PAYLOAD instruction. However this broke
opt_sampler_eot which manually constructs the instruction and so
wasn't setting the header_size. This ends up making the parameters for
the send message all have the wrong location and it all falls apart.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>

src/mesa/drivers/dri/i965/brw_fs.cpp

@@ -2701,6 +2701,7 @@ fs_visitor::opt_sampler_eot()
                                                     load_payload->sources + 1);
 
    new_load_payload->regs_written = load_payload->regs_written + 1;
+   new_load_payload->header_size = 1;
    tex_inst->mlen++;
    tex_inst->header_size = 1;
    tex_inst->insert_before(cfg->blocks[cfg->num_blocks - 1], new_load_payload);