i965/vec4/nir: set the right type for 64-bit registers

Reviewed-by: Matt Turner <mattst88@gmail.com>
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
index 062215d..bdee84b 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
@@ -142,6 +142,9 @@
          reg->num_array_elems == 0 ? 1 : reg->num_array_elems;
       const unsigned num_regs = array_elems * DIV_ROUND_UP(reg->bit_size, 32);
       nir_locals[reg->index] = dst_reg(VGRF, alloc.allocate(num_regs));
+
+      if (reg->bit_size == 64)
+         nir_locals[reg->index].type = BRW_REGISTER_TYPE_DF;
    }
 
    nir_ssa_values = ralloc_array(mem_ctx, dst_reg, impl->ssa_alloc);