Revert "st/glsl_to_tgsi: don't increase immediate index by 1."

This reverts commit 27d456cc87.

DOH, what seems right and what is right with fp64 are always
two different things.

This regressed:
spec@arb_gpu_shader_fp64@shader_storage@layout-std140-fp64-mixed-shader
on radeonsi

Reported-by: Michel Dänzer <michel@daenzer.net>
Cc: "11.2 12.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/mesa/state_tracker/st_glsl_to_tgsi.cpp

@@ -816,7 +816,7 @@ glsl_to_tgsi_visitor::emit_asm(ir_instruction *ir, unsigned op,
 
             if (glsl_base_type_is_64bit(dinst->src[j].type)) {
                dinst->src[j].index = initial_src_idx[j];
-               if (swz > 1 && dinst->src[j].file != PROGRAM_IMMEDIATE) {
+               if (swz > 1) {
                   dinst->src[j].double_reg2 = true;
                   dinst->src[j].index++;
 	       }