intel/compiler: Don't hardcode padding source type to 32bit

We can use LOAD_PAYLOAD infrastructure in order to handle 16bit float
payload. Let's rely on source type for padding sources, if not set
previously then default one would be 32-bit.

This patch will be used later in the series to handle 16-bit float
payloads.

Signed-off-by: Sagar Ghuge <sagar.ghuge@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11766>

src/intel/compiler/brw_fs.cpp

@@ -4037,11 +4037,9 @@ fs_visitor::lower_load_payload()
       }
 
       for (uint8_t i = inst->header_size; i < inst->sources; i++) {
+         dst.type = inst->src[i].type;
          if (inst->src[i].file != BAD_FILE) {
-            dst.type = inst->src[i].type;
             ibld.MOV(dst, inst->src[i]);
-         } else {
-            dst.type = BRW_REGISTER_TYPE_UD;
          }
          dst = offset(dst, ibld, 1);
       }