i965: Use BLORP for color clears on gen4-5

We don't support replicated data clears yet.  Those take a bit more work
and enabling replicated data clears in its own commit is probably better
for bisectibility anyway.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>

src/intel/blorp/blorp_clear.c

@@ -399,6 +399,10 @@ blorp_clear(struct blorp_batch *batch,
    if (surf->surf->tiling == ISL_TILING_LINEAR)
       use_simd16_replicated_data = false;
 
+   /* Replicated clears don't work yet before gen6 */
+   if (batch->blorp->isl_dev->info->gen < 6)
+      use_simd16_replicated_data = false;
+
    /* Constant color writes ignore everyting in blend and color calculator
     * state.  This is not documented.
     */

src/mesa/drivers/dri/i965/brw_clear.c

@@ -285,8 +285,7 @@ brw_clear(struct gl_context *ctx, GLbitfield mask)
          mt->stencil_mt->r8stencil_needs_update = true;
    }
 
-   /* BLORP is currently only supported on Gen6+. */
-   if (brw->gen >= 6 && (mask & BUFFER_BITS_COLOR)) {
+   if (mask & BUFFER_BITS_COLOR) {
       const bool encode_srgb = ctx->Color.sRGBEnabled;
       if (brw_blorp_clear_color(brw, fb, mask, partial_clear, encode_srgb)) {
          debug_mask("blorp color", mask & BUFFER_BITS_COLOR);